You should be able to get your photo pass card from any Universal photographer (they have bright yellow cameras) or at any of the ride photo counters, and use it throughout the day. However, to activate your photo package account you need to go to the photo place near the entrance to either of the parks. You can activate your package any time before the park closes, but if you forget to activate your package before leaving the park for the night, you will lose all the photos on the cards. Photos only stay in Universal's system for the day; once the package is activated, your photos will stay in your account (since they are paid for, they get uploaded to your account throughout the day and you can access them whenever you want). After your account is activated, you do not need to return to the photo place, but you can return in order to add borders, effects, etc.