For subscription, auto-generated invoices are associated with the subscription in each billing cycle. That’s why it is termed as
recurring invoice. So you don’t need to create any invoice explicitly.
Line items and payment amount are determined by the properties of the subscription, as well as by any one-off items added to the subscription.
billing_method = manual, the due date is the invoice creation date plus the value of the subscription’s
billing_method = automatic, the due date doesn’t have any significance.
Recurring invoice can be paid in the following ways :