Just FYI, I'm not even sure these really exist anymore. I had one in my Killzone Shadowfall game case and was going to use for the Destiny Beta- but it expired on 3/31/14. I don't know if other games have them or not.
Also FYI- you may be able to use a 2 day trial PS+ without a code. When I tried to get into the multiplayer part of the Destiny Beta, PSN popped up and offered me a 2 day trial. YMMV of course
