Chris Brown

Gamestop questions( ps vita offer)?

http://www.gamestop.com/collection/trade-in
here, for the vita offer, im planning to trade in my ds games, ds lite, and psp3000, and a memory stick to gamestop. First of all, i am new to gamestop, so i am not familiar with the concept of credits. Do you have to make an account to gain credits? How are they going to remember me if i comeback later? Can anyone tell me anything ihave to know before I go, and the basics of gamestop? Thanks.