Declines can happen for a variety of reasons. When we submit a charge to your bank, they have automated systems that determine whether or not to accept the charge. These systems take various signals into account, such as your spending habits, account balance, and card information like the expiration date and CVC.
Since these signals are constantly changing, a previously successful card might be declined in the future. So if you enter the correct card information, a future charge can still be declined by a bank’s overzealous fraud systems.
If all of the card information seems correct, please contact your bank, inquire for more information and ask for future charges to be accepted. Otherwise, try and use a different card.