Creates a new subscription on an existing customer. Each customer can have up to 500 active or scheduled subscriptions.
When you create a subscription with collection_method=charge_automatically, the first invoice is finalized as part of the request.
The payment_behavior parameter determines the exact behavior of the initial payment.
To start subscriptions where the first invoice always begins in a draft status, use instead.
Schedules provide the flexibility to model more complex billing configurations that change over time.