diff --git a/src/credits/credits.ts b/src/credits/credits.ts
index 4f16e47..9cde6c0 100644
--- a/src/credits/credits.ts
+++ b/src/credits/credits.ts
@@ -21,6 +21,11 @@ export async function getUserCredits(userId: string): Promise<number> {
   return record[0]?.currentCredits || 0;
 }
 
+/**
+ * Update user's current credit balance
+ * @param userId - User ID
+ * @param credits - New credit balance
+ */
 export async function updateUserCredits(userId: string, credits: number) {
   const db = await getDb();
   await db
@@ -29,6 +34,11 @@ export async function updateUserCredits(userId: string, credits: number) {
     .where(eq(userCredit.userId, userId));
 }
 
+/**
+ * Update user's last refresh time
+ * @param userId - User ID
+ * @param date - Last refresh time
+ */
 export async function updateUserLastRefreshAt(userId: string, date: Date) {
   const db = await getDb();
   await db
@@ -63,11 +73,11 @@ export async function saveCreditTransaction({
       type,
       description
     );
-    throw new Error('Invalid params');
+    throw new Error('saveCreditTransaction, invalid params');
   }
   if (!Number.isFinite(amount) || amount === 0) {
     console.error('saveCreditTransaction, invalid amount', userId, amount);
-    throw new Error('Invalid amount');
+    throw new Error('saveCreditTransaction, invalid amount');
   }
   const db = await getDb();
   await db.insert(creditTransaction).values({
@@ -107,18 +117,18 @@ export async function addCredits({
 }) {
   if (!userId || !type || !description) {
     console.error('addCredits, invalid params', userId, type, description);
-    throw new Error('Invalid params');
+    throw new Error('addCredits, invalid params');
   }
   if (!Number.isFinite(amount) || amount <= 0) {
     console.error('addCredits, invalid amount', userId, amount);
-    throw new Error('Invalid amount');
+    throw new Error('addCredits, invalid amount');
   }
   if (
     expireDays !== undefined &&
     (!Number.isFinite(expireDays) || expireDays <= 0)
   ) {
     console.error('addCredits, invalid expire days', userId, expireDays);
-    throw new Error('Invalid expire days');
+    throw new Error('addCredits, invalid expire days');
   }
   // Process expired credits first
   await processExpiredCredits(userId);
@@ -194,11 +204,11 @@ export async function consumeCredits({
 }) {
   if (!userId || !description) {
     console.error('consumeCredits, invalid params', userId, description);
-    throw new Error('Invalid params');
+    throw new Error('consumeCredits, invalid params');
   }
   if (!Number.isFinite(amount) || amount <= 0) {
     console.error('consumeCredits, invalid amount', userId, amount);
-    throw new Error('Invalid amount');
+    throw new Error('consumeCredits, invalid amount');
   }
   // Process expired credits first
   await processExpiredCredits(userId);
diff --git a/src/credits/types.ts b/src/credits/types.ts
index 0b2fab4..0f94a21 100644
--- a/src/credits/types.ts
+++ b/src/credits/types.ts
@@ -9,6 +9,9 @@ export enum CREDIT_TRANSACTION_TYPE {
   EXPIRE = 'EXPIRE',                    // Credits expired
 }
 
+/**
+ * Credit package price
+ */
 export interface CreditPackagePrice {
   priceId: string;                   // Stripe price ID (not product id)
   amount: number;                    // Price amount in currency units (dollars, euros, etc.)
diff --git a/src/lib/auth.ts b/src/lib/auth.ts
index bd4c3c7..bab07b8 100644
--- a/src/lib/auth.ts
+++ b/src/lib/auth.ts
@@ -1,4 +1,6 @@
 import { websiteConfig } from '@/config/website';
+import { addCredits } from '@/credits/credits';
+import { CREDIT_TRANSACTION_TYPE } from '@/credits/types';
 import { getDb } from '@/db/index';
 import { defaultMessages } from '@/i18n/messages';
 import { LOCALE_COOKIE_NAME, routing } from '@/i18n/routing';
@@ -129,6 +131,19 @@ export const auth = betterAuth({
               console.error('Newsletter subscription error:', error);
             }
           }
+          // Add register gift credits to the user if enabled in website config
+          if (
+            websiteConfig.credits.registerGiftCredits.enable &&
+            websiteConfig.credits.registerGiftCredits.credits > 0
+          ) {
+            await addCredits({
+              userId: user.id,
+              amount: websiteConfig.credits.registerGiftCredits.credits,
+              type: CREDIT_TRANSACTION_TYPE.REGISTER_GIFT,
+              description: 'Register gift credits',
+              expireDays: websiteConfig.credits.registerGiftCredits.expireDays,
+            });
+          }
         },
       },
     },