Aprisaiden on 05 June 2011
It is pretty simple.
Games for free from PS+ = you have access to them as long as your subscription is active.
Discounted games/themes/Avatars/DLC = Yours Forever
Free Themes/Avatars/DLC = Yours Forever
Also despite what some fools think the Welcome Back games are not in any way associated with PS+. They are also yours forever.
