Teaming works with a system that allows us not to have to save card numbers. When you join a Group and indicate a card as a payment method for your donation, the bank assigns a pseudonym to your card (an alphanumeric code like this: 490wtvldife38). That pseudonym is what we do keep. Only the bank can decrypt this code at the time of collection. Moreover, it is only valid for Teaming Foundation charges, so no one else can use it. The only data that we do keep is the expiration date of the card, so we can inform you in advance.