Subscription & Billing Management

Dev Kit for AI provides a complete subscription management system built on Stripe, handling the full lifecycle from checkout to cancellation. This guide covers all billing workflows, subscription states, and use cases for SaaS monetization.

Subscription Lifecycle Overview

The subscription system manages the complete payment lifecycle through Stripe integration:

Subscription States

State	Description	User Access
`active`	Subscription is current and paid	Full access
`trialing`	User is in a trial period	Full access
`past_due`	Payment failed, retrying	Limited access (configurable)
`cancelled`	Subscription ended	No access
`incomplete`	Initial payment pending	No access
`paused`	Subscription temporarily paused	No access
`unpaid`	All payment retries exhausted	No access

Core Billing Workflows

Checkout Session Flow

When a user subscribes, the system creates a Stripe Checkout Session and redirects them to Stripe’s hosted payment page:

Webhook Event Processing

Cloud API processes Stripe webhook events to maintain subscription state:

Handled Webhook Events

Event	Action Taken
`checkout.session.completed`	Create subscription, link Stripe customer to user
`customer.subscription.created`	Record new subscription with status and period
`customer.subscription.updated`	Update status, plan, or cancellation flags
`customer.subscription.deleted`	Mark subscription as cancelled
`invoice.paid`	Record payment, extend subscription period
`invoice.payment_failed`	Mark subscription as past_due
`charge.refunded`	Record refund in payment history

Use Case Scenarios

Dev Kit for AI handles all common subscription scenarios out of the box:

New Subscription

A user without an existing subscription initiates checkout, completes payment, and receives an active subscription:

The system creates a Stripe customer record and stores stripe_customer_id on the user for future transactions.

Returning Customer

When a user who previously had a subscription (cancelled or expired) subscribes again, the system reuses their existing Stripe customer ID:

Returning customers see their saved payment methods in Stripe Checkout, enabling faster re-subscription.

Duplicate Prevention

If a user with an active subscription attempts to start another checkout, the system blocks it and directs them to manage their existing subscription:

// Cloud API validates subscription status before creating checkout
const existingSubscription = await getActiveSubscription(userId, projectId);
if (existingSubscription) {
  return { error: "Active subscription exists", redirectTo: "/billing" };
}

Upgrade/Downgrade

Users can change their subscription plan through the customer portal or update API:

Change Type	Billing Behavior
Upgrade	Prorated charge immediately
Downgrade	Credit applied to next invoice

Cancellation

Users can cancel their subscription immediately or at the end of the billing period:

Cancel at Period End
Cancel Immediately

User retains access until the current billing period expires.

Uncancellation

When a user who scheduled cancellation at period end changes their mind, they can restore their subscription:

Users can manage their subscription through the Stripe Customer Portal, accessible via the /customer-portal endpoint.

Subscription Renewal

When recurring billing succeeds, the system records the payment and extends the subscription:

Trial Periods

Subscriptions can include trial periods where users access features before their first payment:

Payment Failure

When a recurring payment fails, Stripe automatically retries and the system tracks the status:

Configure your application to gracefully degrade or restrict access for users with past_due subscriptions.

Customer Portal Access

Users can manage their subscription through Stripe’s hosted customer portal:

Subscription Data Model

The Cloud API stores subscription data with these key fields:

Field	Type	Description
`id`	UUID	Unique subscription identifier
`user_id`	UUID	Associated end user
`project_id`	UUID	Project scope
`stripe_subscription_id`	string	Stripe subscription ID
`stripe_customer_id`	string	Stripe customer ID
`status`	enum	Current subscription state
`price_id`	string	Stripe price ID for the plan
`current_period_start`	timestamp	Current billing period start
`current_period_end`	timestamp	Current billing period end
`cancel_at_period_end`	boolean	Scheduled for cancellation
`cancelled_at`	timestamp	When cancellation was requested

Payment History

All transactions are recorded for user access and developer reporting:

End-User Billing Endpoints

End users access their billing information through these Cloud API endpoints:

Get My Subscription

Retrieve current subscription status, plan, and billing period

Get My Payments

List payment history with amounts, dates, and statuses

Customer Portal

Access Stripe’s self-service billing portal

Cancel Subscription

Cancel subscription immediately or at period end

Update Subscription

Upgrade or downgrade to a different plan

Developer Analytics

Developers can monitor subscription and payment metrics through Cloud Admin or the API:

Aggregated Statistics

The /api/v1/payments/stats endpoint provides:

Total active subscriptions
Total revenue (by period)
Subscription counts by status
Transaction counts and totals

Per-Project Analytics

Each project’s Payments tab in Cloud Admin displays: (((REPLACE_THIS_WITH_IMAGE: console-project-payments-analytics.png: Project payments tab showing subscription stats, transaction history, and revenue metrics)))

Active subscription count
Monthly recurring revenue
Recent transactions
Subscription/cancellation trends

Integration Checklist

Configure Stripe

Set up API keys and webhook endpoints in Cloud Admin

Create Stripe Products

Define your subscription plans in the Stripe Dashboard

Implement Checkout UI

Add subscription buttons that call the checkout session endpoint

Handle Subscription States

Check user subscription status to gate access to premium features

Add Billing Management

Implement billing UI components for end users

Test Thoroughly

Use Stripe test mode to verify all workflows

Next Steps

Payment Setup

Configure Stripe credentials and webhooks

Monitor in Cloud Admin

View and manage subscriptions in the console

Starter Kit Billing

Implement billing UI in your application

Payment API Reference

Complete endpoint documentation

Welcome

Core Concepts

Features

Subscription & Billing Management

Subscription Lifecycle Overview

Subscription States

Core Billing Workflows

Checkout Session Flow

Webhook Event Processing

Handled Webhook Events

Use Case Scenarios

New Subscription

Returning Customer

Duplicate Prevention

Upgrade/Downgrade

Cancellation

Uncancellation

Subscription Renewal

Trial Periods

Payment Failure

Customer Portal Access

Subscription Data Model

Payment History

End-User Billing Endpoints

Get My Subscription

Get My Payments

Customer Portal

Cancel Subscription

Update Subscription

Developer Analytics

Aggregated Statistics

Per-Project Analytics

Integration Checklist

Next Steps

Payment Setup

Monitor in Cloud Admin

Starter Kit Billing

Payment API Reference

​Subscription Lifecycle Overview

​Subscription States

​Core Billing Workflows

​Checkout Session Flow

​Webhook Event Processing

​Handled Webhook Events

​Use Case Scenarios

​New Subscription

​Returning Customer

​Duplicate Prevention

​Upgrade/Downgrade

​Cancellation

​Uncancellation

​Subscription Renewal

​Trial Periods

​Payment Failure

​Customer Portal Access

​Subscription Data Model

​Payment History

​End-User Billing Endpoints

Get My Subscription

Get My Payments

Customer Portal

Cancel Subscription

Update Subscription

​Developer Analytics

​Aggregated Statistics

​Per-Project Analytics

​Integration Checklist

​Next Steps

Payment Setup

Monitor in Cloud Admin

Starter Kit Billing

Payment API Reference

Subscription Lifecycle Overview

Subscription States

Core Billing Workflows

Checkout Session Flow

Webhook Event Processing

Handled Webhook Events

Use Case Scenarios

New Subscription

Returning Customer

Duplicate Prevention

Upgrade/Downgrade

Cancellation

Uncancellation

Subscription Renewal

Trial Periods

Payment Failure

Customer Portal Access

Subscription Data Model

Payment History

End-User Billing Endpoints

Developer Analytics

Aggregated Statistics

Per-Project Analytics

Integration Checklist

Next Steps