diff --git a/license-service/src/main/java/com/xuqm/license/controller/LicenseInternalController.java b/license-service/src/main/java/com/xuqm/license/controller/LicenseInternalController.java
index 83f25c9..bbcf76e 100644
--- a/license-service/src/main/java/com/xuqm/license/controller/LicenseInternalController.java
+++ b/license-service/src/main/java/com/xuqm/license/controller/LicenseInternalController.java
@@ -81,15 +81,17 @@ public class LicenseInternalController {
     }
 
     @GetMapping("/devices/{deviceId}")
-    public ResponseEntity<ApiResponse<DeviceEntity>> getDevice(
+    public ResponseEntity<ApiResponse<List<DeviceEntity>>> getDevice(
             @RequestHeader(value = "X-Internal-Token", required = false) String token,
             @PathVariable String deviceId) {
         if (!isAllowed(token)) {
             return ResponseEntity.status(403).body(ApiResponse.error(403, "Forbidden"));
         }
-        return deviceService.findByDeviceId(deviceId)
-                .map(d -> ResponseEntity.ok(ApiResponse.success(d)))
-                .orElse(ResponseEntity.ok(ApiResponse.error(404, "Device not found")));
+        List<DeviceEntity> devices = deviceService.findByDeviceId(deviceId);
+        if (devices.isEmpty()) {
+            return ResponseEntity.ok(ApiResponse.error(404, "Device not found"));
+        }
+        return ResponseEntity.ok(ApiResponse.success(devices));
     }
 
     private boolean isAllowed(String token) {
diff --git a/license-service/src/main/java/com/xuqm/license/entity/DeviceEntity.java b/license-service/src/main/java/com/xuqm/license/entity/DeviceEntity.java
index 82603a5..8326bb8 100644
--- a/license-service/src/main/java/com/xuqm/license/entity/DeviceEntity.java
+++ b/license-service/src/main/java/com/xuqm/license/entity/DeviceEntity.java
@@ -4,10 +4,12 @@ import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+import jakarta.persistence.UniqueConstraint;
 import java.time.LocalDateTime;
 
 @Entity
-@Table(name = "devices")
+@Table(name = "devices",
+    uniqueConstraints = @UniqueConstraint(name = "uk_app_key_device_id", columnNames = {"app_key", "device_id"}))
 public class DeviceEntity {
 
     @Id
diff --git a/license-service/src/main/java/com/xuqm/license/repository/DeviceRepository.java b/license-service/src/main/java/com/xuqm/license/repository/DeviceRepository.java
index 3bff6de..0185d0b 100644
--- a/license-service/src/main/java/com/xuqm/license/repository/DeviceRepository.java
+++ b/license-service/src/main/java/com/xuqm/license/repository/DeviceRepository.java
@@ -9,7 +9,8 @@ import java.util.Optional;
 
 @Repository
 public interface DeviceRepository extends JpaRepository<DeviceEntity, String> {
-    Optional<DeviceEntity> findByDeviceId(String deviceId);
+    Optional<DeviceEntity> findByAppKeyAndDeviceId(String appKey, String deviceId);
+    List<DeviceEntity> findByDeviceId(String deviceId);
     List<DeviceEntity> findByAppKeyOrderByRegisteredAtDesc(String appKey);
     long countByAppKeyAndIsActiveTrue(String appKey);
 }
diff --git a/license-service/src/main/java/com/xuqm/license/service/DeviceService.java b/license-service/src/main/java/com/xuqm/license/service/DeviceService.java
index b7b8fdb..4454474 100644
--- a/license-service/src/main/java/com/xuqm/license/service/DeviceService.java
+++ b/license-service/src/main/java/com/xuqm/license/service/DeviceService.java
@@ -34,7 +34,7 @@ public class DeviceService {
         this.objectMapper = objectMapper;
     }
 
-    public Optional<DeviceEntity> findByDeviceId(String deviceId) {
+    public List<DeviceEntity> findByDeviceId(String deviceId) {
         return deviceRepository.findByDeviceId(deviceId);
     }
 
@@ -48,8 +48,8 @@ public class DeviceService {
                                    JsonNode userInfo) {
         validatePackageName(appKey, packageName);
 
-        // Check if device already registered
-        Optional<DeviceEntity> existingOpt = findByDeviceId(deviceId);
+        // Check if device already registered for this app
+        Optional<DeviceEntity> existingOpt = deviceRepository.findByAppKeyAndDeviceId(appKey, deviceId);
         if (existingOpt.isPresent()) {
             DeviceEntity existing = existingOpt.get();
             if (!Boolean.TRUE.equals(existing.getIsActive())) {
@@ -126,7 +126,7 @@ public class DeviceService {
             return new VerifyResult(false, "Token mismatch");
         }
 
-        DeviceEntity device = findByDeviceId(deviceId).orElse(null);
+        DeviceEntity device = deviceRepository.findByAppKeyAndDeviceId(appKey, deviceId).orElse(null);
         if (device == null || !Boolean.TRUE.equals(device.getIsActive())) {
             return new VerifyResult(false, "Device not found or deactivated");
         }