What you entered before was likely the early access key. If you purchased the game digitally, check your e-mail for another e-mail that has your product key. The sender from SQEX is something like webmail-v4 or something so it's probably in your spam folder.

Then just make sure when you do register it that you don't make a new service account for it, choose to add a windows or PS3 service and it should clearly show your account and the number of characters on it before you confirm to add the key to it