This usually occurs when Google or Apple tries to renew the subscription, but there is a problem with the card. Sometimes it can be something as simple as a billing address change (you moved) or a new card was issued with a new expiration date, or it can also be due to insufficient funds. Usually, it can be fixed by just go to your account and update your Payment Method. Follow the instructions below:
Go to the following link in the Play Store: Manage PaymentsAlong the left side of the screen, select Bills and accounts.
Go to the following link in iTunes: Manage Subscription
Go to the following link in the Play Store: Manage Payments