EA has been offering up free games on their Origin marketplace for a few months now, with their “On the house” program. It’s a simple program, that only requires you have Origin installed on your computer to take advantage of.
Just a short while ago they revealed that a free version of Plants vs. Zombies was on the house, and now today, Battlefield 3 has been added to that list.
Those who claim these free games on Origin have a no strings attached ability to keep them forever. Though if you want the free games you should probably act quickly, the freebies are only available for a limited time, and then they go back to being full price.