diff --git a/license/service.go b/license/service.go
index 266d042..f07b4a7 100644
--- a/license/service.go
+++ b/license/service.go
@@ -20,7 +20,13 @@ func GenerateLicenseHandler(db storage.Database) fiber.Handler {
 			return fiber.NewError(fiber.StatusBadRequest, "Missing machine ID")
 		}
 
-		// ⚠️ 此时不设置 Expiry 字段，由 Activate 阶段设置
+		// ✅ 检查是否已经生成过
+		if db.HasGenerated(req.MachineID) {
+			return fiber.NewError(fiber.StatusForbidden, "License already generated for this machine")
+		}
+
+		// ❌ 不再接收客户端传的 Expiry，由后续激活阶段设置
+		req.Expiry = ""
 
 		payloadBytes, err := json.Marshal(req)
 		if err != nil {
@@ -37,6 +43,9 @@ func GenerateLicenseHandler(db storage.Database) fiber.Handler {
 			Signature: signature,
 		}
 
+		// ✅ 保存生成记录（避免重复）
+		db.SaveGenerated(req.MachineID, licenseFile.Payload+"."+licenseFile.Signature)
+
 		return c.JSON(licenseFile)
 	}
 }
diff --git a/storage/db.go b/storage/db.go
index 62e5ddc..ba1ce68 100644
--- a/storage/db.go
+++ b/storage/db.go
@@ -17,6 +17,11 @@ func InitDB() Database {
         machine_id TEXT UNIQUE,
         license TEXT,
         activated INTEGER
+    )`)
+	db.Exec(`CREATE TABLE IF NOT EXISTS generations (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        machine_id TEXT UNIQUE,
+        license TEXT
     )`)
 	return Database{db}
 }
@@ -32,3 +37,15 @@ func (d Database) SaveActivation(machineID string, licenseText string) {
 	d.db.Exec("INSERT OR REPLACE INTO activations(machine_id, license, activated) VALUES (?, ?, 1)",
 		machineID, licenseText)
 }
+
+func (d Database) HasGenerated(machineID string) bool {
+	row := d.db.QueryRow("SELECT license FROM generations WHERE machine_id = ?", machineID)
+	var license string
+	err := row.Scan(&license)
+	return err == nil
+}
+
+func (d Database) SaveGenerated(machineID string, licenseText string) {
+	d.db.Exec("INSERT OR REPLACE INTO generations(machine_id, license) VALUES (?, ?)",
+		machineID, licenseText)
+}