https://www.origin.com/en-us/store/f.../on-the-house?

About 'On the House'
Free?! What's the catch?
There's no catch. Grab full games, expansions and more at absolutely no cost. Just make sure to act fast because On the House specials can appear and disappear at any time.
You mean a trial or demo, right?
Nope. You’re getting a full version of the real game — for free!
How long will I own the game?
Once you’ve claimed your game, it’s yours to keep!
Why is Origin doing this?
Our goal is to provide a great gaming experience and a way to discover awesome new games. Having a game in your library, for free, is a fantastic way to see what Origin is all about.