If you got as far as credit card information, then the key was never registered before. Once a key has been registered, it is permanently on the account- it can't be removed, even by cancelling the account. Seeing as how you got that far, the free 30 days will apply. you do have to enter credit card or game card information to finish the account initializaion process, but you will not be charged until the 30 days are up, and you can cancel the account anytime by editing your billing information at https://secure.station.sony.com/mxo/