Apple has recently announced that they will be adding a grace period for auto-renewals on the App Store. Subscribers who haven’t updated their billing credentials by the due date will have their premium features deactivated until they enter new billing information.
The grace period acts as the length of time when the subscriber can still access the premium features and possibly have their billing problems fixed. Grace period will actually depend on the subscription length.
For instance, 7-day subscriptions may have a 6-day grace period, while longer subscriptions may have a grace period of up to 16 days. Apple mentions that interruption of service or premium features will not happen if the subscriber has made a successful repayment within the time frame.
Developers whose apps have subscription services can implement the billing grace period feature right away. This information is available to read at the official Apple developer site.