Content locks. Then user is supposed to complete an offer and receive access to content ("unlocking" of the lock). So this thread is about the best way to unlock the lock. I know of 2 ways: 1) gateway unlocks after fixed X time period regardless of whether the user actually completed an offer or not 2) postback, which means your server is constantly checking with the CPA network's server to see if the user has completed the offer. What is a better way? What provides better conversion ratios? Better user experience? What's better overall and why?