So if you're already comfortable building your own carts using Checkout, you're ready to implement Subscriptions by consulting the documentation. Each billing recurrence is a new order, so everything you've learned about processing orders still applies. You can let us create these billing recurrences for you with Google-Handled Subscriptions, or if you'd like more control, you can create these recurrences yourself with Merchant-Handled Subscriptions.
Please try this feature out, and let us know what you think. If you're a member of our Developer's Forum, you can ask questions and leave feedback here. You can also suggest other new Checkout features here.
Andrew Cunningham