You have until August 14th to add Battlefield 4 for a week of free game time (168 hours). Don’t believe anything is restricted.
There’s also a game time promo for Kingdoms of Amalur: Reckoning. Add the game and you get 48 hours of game time.
Both games are also on sale.
Battlefield 4 Standard Edition $19.79
Battlefield 4 Digital Deluxe Edition $26.39
Battlefield 4 + Premium $52
Kindoms of Amalur: Reckoning $10
See more details here.