(PS4 & PS3 versions) are free on PSN. Go to the link below and buy the free PS4 demo. After you've purchased it, the PS3 and PS4 full games can be bought for free. Possibly a glitch. Best do it before Sony fixes it. Link
Odd glitch, but it did work
Anyway it was not first time PSN had glitch.
Because when I logged in into my PSN account (yeah, I don't have Play Station but Free Playstation Games :P )It has 3 games Mirror's Edge, NFS Most Wanted, PvZ Garden Warfare.
EDIT: I think this glitch is still working.
You have to go on game page and click on Try Demo.
On checkout page it don't say DEMO.