A third party processes TpT's credit card transactions but we do have a feature that allows you to store your credit card information for a quicker, more convenient checkout experience.
The next time you use your credit card on TpT, just check the "save this credit/debit card with our payment processor to use for future purchases" box under Card Information. The next time you make a purchase, you can choose to pay with that card by default. Or you can enter a new card for one-time use, or to replace the saved one. You can only store one card at a time.