Add a new saved credit card to save your card info and easily purchase masters on a per-track basis without having to re-enter your information each time.
Tick off the 'Save this card for later' box to save that credit card when you’re making a per-track purchase.
You can also add a saved card by going to your Account settings and then to the 'Edit Payment Methods' page. Click on 'ADD A NEW CARD', enter your info and save it.
Keep in mind that these cards don’t have anything to do with your subscription payment method.