diff --git a/internal/handler/admin.go b/internal/handler/admin.go
index 3b35390..1840f1f 100644
--- a/internal/handler/admin.go
+++ b/internal/handler/admin.go
@@ -43,6 +43,7 @@ func createUserHandler(svc *service.Container) gin.HandlerFunc {
 			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 			return
 		}
+		refreshLicenseCapacityBestEffort(c.Request.Context(), svc)
 		u, _, err := svc.Auth.Register(c.Request.Context(), req.Username, req.Password)
 		if err != nil {
 			writeUserMutationError(c, svc, err)
diff --git a/internal/handler/auth.go b/internal/handler/auth.go
index 41547c5..19855db 100644
--- a/internal/handler/auth.go
+++ b/internal/handler/auth.go
@@ -62,6 +62,7 @@ func registerHandler(svc *service.Container) gin.HandlerFunc {
 			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 			return
 		}
+		refreshLicenseCapacityBestEffort(c.Request.Context(), svc)
 		u, tokens, err := svc.Auth.Register(c.Request.Context(), req.Username, req.Password)
 		if err != nil {
 			if errors.Is(err, service.ErrUsernameTaken) {
diff --git a/internal/handler/license.go b/internal/handler/license.go
index 936a122..12d0bd7 100644
--- a/internal/handler/license.go
+++ b/internal/handler/license.go
@@ -29,7 +29,10 @@ const (
 )
 
 type licenseActivateReq struct {
-	Key        string `json:"key" binding:"required"`
+	Key string `json:"key" binding:"required"`
+	// DeviceID is accepted for wire compatibility with older web clients but is
+	// intentionally ignored. Licensing binds to this MediaStationGo server
+	// instance, not to the browser that opened the admin page.
 	DeviceID   string `json:"device_id"`
 	DeviceName string `json:"device_name"`
 }
@@ -71,7 +74,7 @@ func licenseActivateHandler(svc *service.Container) gin.HandlerFunc {
 			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 			return
 		}
-		deviceID, err := ensureLicenseDeviceID(c.Request.Context(), svc, req.DeviceID)
+		deviceID, err := ensureLicenseDeviceID(c.Request.Context(), svc, "")
 		if err != nil {
 			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 			return
@@ -162,6 +165,13 @@ func licenseHeartbeatHandler(svc *service.Container) gin.HandlerFunc {
 	}
 }
 
+func refreshLicenseCapacityBestEffort(ctx context.Context, svc *service.Container) {
+	if svc == nil || svc.Repo == nil || svc.Repo.Setting == nil {
+		return
+	}
+	_, _, _ = maybeSendLicenseHeartbeat(ctx, svc, 0)
+}
+
 // RunLicenseHeartbeatLoop keeps the license server aware of active deployments.
 // The loop checks periodically, but only sends when the last stored heartbeat is
 // older than licenseHeartbeatInterval.
@@ -431,6 +441,7 @@ func licenseActivationView(state service.LicenseActivationState) gin.H {
 	return gin.H{
 		"id":              state.DeviceID,
 		"key_id":          state.LicenseType,
+		"key":             maskLicenseKey(state.LicenseKey),
 		"device_id":       state.DeviceID,
 		"device_name":     state.DeviceName,
 		"plan":            state.LicenseType,
@@ -444,6 +455,17 @@ func licenseActivationView(state service.LicenseActivationState) gin.H {
 	}
 }
 
+func maskLicenseKey(key string) string {
+	key = strings.TrimSpace(key)
+	if key == "" {
+		return ""
+	}
+	if len(key) <= 8 {
+		return key
+	}
+	return key[:5] + "..." + key[len(key)-4:]
+}
+
 func licenseStatusMessage(active bool, clientErr error) string {
 	if active {
 		return "已激活"
diff --git a/internal/handler/license_client.go b/internal/handler/license_client.go
index 5ecf5f9..1046659 100644
--- a/internal/handler/license_client.go
+++ b/internal/handler/license_client.go
@@ -36,9 +36,13 @@ func newLicenseClient(ctx context.Context, svc *service.Container) (*licenseClie
 	if baseURL == "" {
 		return nil, errors.New("license server url not configured")
 	}
+	secret = strings.TrimSpace(secret)
+	if secret == "" {
+		return nil, errors.New("license hmac secret not configured")
+	}
 	return &licenseClient{
 		baseURL:    baseURL,
-		hmacSecret: strings.TrimSpace(secret),
+		hmacSecret: secret,
 		httpClient: &http.Client{Timeout: 15 * time.Second},
 	}, nil
 }
@@ -93,7 +97,10 @@ func (c *licenseClient) do(req *http.Request, out any) error {
 
 func (c *licenseClient) verifySigned(resp *licenseServerSignedResp) error {
 	if c.hmacSecret == "" {
-		return nil
+		return errors.New("license hmac secret not configured")
+	}
+	if strings.TrimSpace(resp.Signature) == "" {
+		return errors.New("license server signature missing")
 	}
 	unsigned := struct {
 		Valid         bool    `json:"valid"`
diff --git a/internal/handler/license_test.go b/internal/handler/license_test.go
index 8800cef..4f110bd 100644
--- a/internal/handler/license_test.go
+++ b/internal/handler/license_test.go
@@ -1,12 +1,23 @@
 package handler
 
 import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 	"time"
 
+	"github.com/ShukeBta/MediaStationGo/internal/config"
+	"github.com/ShukeBta/MediaStationGo/internal/model"
+	"github.com/ShukeBta/MediaStationGo/internal/repository"
 	"github.com/ShukeBta/MediaStationGo/internal/service"
+	"github.com/gin-gonic/gin"
+	"github.com/glebarez/sqlite"
+	"gorm.io/gorm"
 )
 
 func TestLicenseStatusMaxUsersUsesLicensedLimit(t *testing.T) {
@@ -157,3 +168,108 @@ func TestLicenseHeartbeatEligibleRequiresActivationState(t *testing.T) {
 		t.Fatalf("valid license state should trigger automatic license heartbeat")
 	}
 }
+
+func TestLicenseActivateBindsServerInstanceNotBrowserFingerprint(t *testing.T) {
+	var upstreamFingerprint string
+	maxUsers := 60
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var payload map[string]any
+		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
+			t.Fatalf("decode upstream payload: %v", err)
+		}
+		upstreamFingerprint, _ = payload["fingerprint"].(string)
+		resp := licenseServerSignedResp{
+			Valid:         true,
+			LicenseType:   "subscription",
+			MaxDevices:    3,
+			MaxUsers:      &maxUsers,
+			NextHeartbeat: time.Now().Add(time.Hour).Format(time.RFC3339),
+		}
+		resp.Signature = signLicenseTestPayload("test-secret", resp)
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(resp)
+	}))
+	defer upstream.Close()
+
+	svc := newLicenseHandlerTestService(t)
+	if err := svc.Repo.Setting.Set(t.Context(), licenseServerURLSetting, upstream.URL); err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.Repo.Setting.Set(t.Context(), licenseHMACSecretSetting, "test-secret"); err != nil {
+		t.Fatal(err)
+	}
+
+	router := gin.New()
+	router.POST("/license/activate", licenseActivateHandler(svc))
+	req := httptest.NewRequest(http.MethodPost, "/license/activate", strings.NewReader(`{
+		"key": "MS-ABCD-EFGH-JKLM-NPQR",
+		"device_id": "browser-fingerprint",
+		"device_name": ""
+	}`))
+	req.Header.Set("Content-Type", "application/json")
+	w := httptest.NewRecorder()
+	router.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("activate status = %d body=%s", w.Code, w.Body.String())
+	}
+	if upstreamFingerprint == "" || upstreamFingerprint == "browser-fingerprint" || !strings.HasPrefix(upstreamFingerprint, "msgo-") {
+		t.Fatalf("activation should use server-generated msgo id, got %q", upstreamFingerprint)
+	}
+	stored, err := svc.Repo.Setting.Get(t.Context(), licenseDeviceIDSetting)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if stored != upstreamFingerprint {
+		t.Fatalf("stored device id = %q, upstream fingerprint = %q", stored, upstreamFingerprint)
+	}
+}
+
+func TestNewLicenseClientRequiresHMACSecret(t *testing.T) {
+	svc := newLicenseHandlerTestService(t)
+	if err := svc.Repo.Setting.Set(t.Context(), licenseServerURLSetting, "http://127.0.0.1:8001"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := newLicenseClient(t.Context(), svc); err == nil || !strings.Contains(err.Error(), "hmac secret") {
+		t.Fatalf("expected missing hmac secret error, got %v", err)
+	}
+}
+
+func newLicenseHandlerTestService(t *testing.T) *service.Container {
+	t.Helper()
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.AutoMigrate(&model.Setting{}); err != nil {
+		t.Fatal(err)
+	}
+	return &service.Container{
+		Cfg:  &config.Config{},
+		Repo: repository.New(db),
+	}
+}
+
+func signLicenseTestPayload(secret string, resp licenseServerSignedResp) string {
+	unsigned := struct {
+		Valid         bool    `json:"valid"`
+		LicenseType   string  `json:"license_type"`
+		ExpiryDate    *string `json:"expiry_date"`
+		MaxDevices    int     `json:"max_devices"`
+		MaxUsers      *int    `json:"max_users"`
+		DaysRemaining *int    `json:"days_remaining"`
+		NextHeartbeat string  `json:"next_heartbeat"`
+	}{
+		Valid:         resp.Valid,
+		LicenseType:   resp.LicenseType,
+		ExpiryDate:    resp.ExpiryDate,
+		MaxDevices:    resp.MaxDevices,
+		MaxUsers:      resp.MaxUsers,
+		DaysRemaining: resp.DaysRemaining,
+		NextHeartbeat: resp.NextHeartbeat,
+	}
+	payload, _ := json.Marshal(unsigned)
+	mac := hmac.New(sha256.New, []byte(secret))
+	_, _ = mac.Write(payload)
+	return hex.EncodeToString(mac.Sum(nil))
+}
diff --git a/web/src/api/license.ts b/web/src/api/license.ts
index 4e64e67..b475f35 100644
--- a/web/src/api/license.ts
+++ b/web/src/api/license.ts
@@ -33,13 +33,6 @@ export interface LicenseStatus {
   message?: string
 }
 
-/** Generate a short device fingerprint from browser/OS info. */
-function deviceFingerprint(): string {
-  const nav = window.navigator
-  const parts = [nav.hardwareConcurrency, nav.language, screen.width, screen.height]
-  return btoa(parts.join('|')).slice(0, 32).replace(/[+/=]/g, '')
-}
-
 // ── API methods ──
 
 export const licenseAPI = {
@@ -48,8 +41,6 @@ export const licenseAPI = {
     api
       .post<LicenseActivation>('/license/activate', {
         key: key.trim(),
-        device_id: deviceFingerprint(),
-        device_name: navigator.platform || 'Web Client',
       })
       .then((r) => r.data),
 
diff --git a/web/src/pages/LicensePageSections.tsx b/web/src/pages/LicensePageSections.tsx
index 1a369b3..4ddc0fb 100644
--- a/web/src/pages/LicensePageSections.tsx
+++ b/web/src/pages/LicensePageSections.tsx
@@ -18,7 +18,7 @@ export function LicenseHeader() {
       </div>
       <div>
         <h1 className="font-display text-3xl font-bold text-ink-600">许可证</h1>
-        <p className="text-sm text-ink-50">绑定授权密钥以解锁全部功能</p>
+        <p className="text-sm text-ink-50">绑定授权密钥以提升多用户容量</p>
       </div>
     </div>
   )
@@ -55,7 +55,7 @@ export function LicenseBindPanel({
         </button>
       </form>
       <p className="text-xs text-sand-500">
-        输入从授权服务器获取的许可证密钥，激活后即可使用所有高级功能。
+        输入从授权服务器获取的许可证密钥，激活后按授权额度开放更多平台用户。
       </p>
     </div>
   )
@@ -126,7 +126,7 @@ export function LicenseStatusPanel({
 
       {active && activation && (
         <div className="grid grid-cols-2 gap-3">
-          <StatusBadge label="密钥" value={activation.key ?? activation.key_id} mono />
+          <StatusBadge label="密钥" value={activation.key || activation.key_id} mono />
           <StatusBadge
             label="套餐"
             value={activation.plan ?? 'standard'}
diff --git a/web/src/pages/settingsGroupGeneral.ts b/web/src/pages/settingsGroupGeneral.ts
index 0e5bcd7..4c6807f 100644
--- a/web/src/pages/settingsGroupGeneral.ts
+++ b/web/src/pages/settingsGroupGeneral.ts
@@ -122,7 +122,7 @@ export const licenseSettingsGroup: SettingGroup = {
       key: 'license.hmac_secret',
       label: 'HMAC 签名密钥',
       type: 'text',
-      hint: '必须与 License Server 的 LICENSE_HMAC_SECRET 保持一致；留空则跳过响应签名校验。',
+      hint: '必须与 License Server 的 LICENSE_HMAC_SECRET 保持一致；用于校验多用户授权响应签名。',
     },
   ],
 }