diff --git a/packages/shared-billing/src/config/billing.config.ts b/packages/shared-billing/src/config/billing.config.ts
index a95412e..df9ffb4 100644
--- a/packages/shared-billing/src/config/billing.config.ts
+++ b/packages/shared-billing/src/config/billing.config.ts
@@ -74,7 +74,7 @@ export const loadBillingConfig = (): BillingConfig => ({
       darkWebScans: 12,
     },
     plus: {
-      priceId: process.env.STRIPE_PLUS_TIER_PRICE_ID!,
+      priceId: process.env.STRIPE_PLUS_TIER_PRICE_ID || 'price_plus',
       monthlyPriceCents: 1999,
       callMinutesLimit: 2000,
       smsCountLimit: 10000,
@@ -82,7 +82,7 @@ export const loadBillingConfig = (): BillingConfig => ({
       voiceCloning: true,
     },
     premium: {
-      priceId: process.env.STRIPE_PREMIUM_TIER_PRICE_ID!,
+      priceId: process.env.STRIPE_PREMIUM_TIER_PRICE_ID || 'price_premium',
       monthlyPriceCents: 4999,
       callMinutesLimit: 10000,
       smsCountLimit: 50000,
diff --git a/packages/shared-billing/src/index.ts b/packages/shared-billing/src/index.ts
index 8a4cc67..96be282 100644
--- a/packages/shared-billing/src/index.ts
+++ b/packages/shared-billing/src/index.ts
@@ -4,6 +4,7 @@ export {
   requireTier,
   checkUsageLimit,
   withUsageTracking,
+  withSubscription,
   requireSubscription,
 } from './middleware/billing.middleware';
 
diff --git a/packages/shared-billing/src/middleware/billing.middleware.ts b/packages/shared-billing/src/middleware/billing.middleware.ts
index 1ff9ee2..7fce136 100644
--- a/packages/shared-billing/src/middleware/billing.middleware.ts
+++ b/packages/shared-billing/src/middleware/billing.middleware.ts
@@ -7,7 +7,8 @@ const billingService = BillingService.getInstance();
 export interface AuthenticatedRequest extends Request {
   userId?: string;
   tier?: SubscriptionTier;
-  usage?: { current: number; limit: number; remaining: number };
+  usage?: { current: number; limit: number; remaining: number; withinLimit: boolean };
+  subscriptionId?: string;
 }
 
 export function requireTier(
@@ -108,24 +109,52 @@ export function withUsageTracking(
   };
 }
 
+export function withSubscription() {
+  return async (
+    req: AuthenticatedRequest,
+    res: Response,
+    next: NextFunction
+  ): Promise<void> => {
+    const { userId, tier } = req;
+
+    if (!userId || !tier) {
+      next();
+      return;
+    }
+
+    try {
+      // Fetch subscription from database
+      // TODO: Replace with actual database query
+      const subscriptionId = (req as any).subscriptionId;
+      
+      if (subscriptionId) {
+        req.subscriptionId = subscriptionId;
+      }
+
+      next();
+    } catch (error) {
+      res.status(500).json({
+        error: 'Failed to fetch subscription',
+        message: error instanceof Error ? error.message : 'Unknown error',
+      });
+    }
+  };
+}
+
 export function requireSubscription() {
   return async (
     req: AuthenticatedRequest,
     res: Response,
     next: NextFunction
   ): Promise<void> => {
-    const { userId } = req;
+    const { userId, subscriptionId } = req;
 
     if (!userId) {
       res.status(401).json({ error: 'Authentication required' });
       return;
     }
 
-    // Check if user has active subscription
-    // This would typically query the database
-    const hasSubscription = (req as any).subscriptionId != null;
-
-    if (!hasSubscription) {
+    if (!subscriptionId) {
       res.status(402).json({
         error: 'Active subscription required',
       });
diff --git a/packages/shared-billing/src/services/billing.service.ts b/packages/shared-billing/src/services/billing.service.ts
index 0e49a62..cc4a4ed 100644
--- a/packages/shared-billing/src/services/billing.service.ts
+++ b/packages/shared-billing/src/services/billing.service.ts
@@ -132,7 +132,14 @@ export class BillingService {
   ): Promise<Stripe.Invoice> {
     return await stripe.invoices.create({
       customer: customerId,
-      metadata: { ...metadata, description },
+      line_items: [
+        {
+          amount_data: { currency: 'usd', unit_amount: amount },
+          description: description,
+          quantity: 1,
+        },
+      ],
+      metadata: metadata,
     });
   }