Ps3 free game trial expiry time limit.?

i wanted to ask that there are free game trials in ps3 that expire after 60 minutes, the list include GoW 1 , 2. dante's inferno, etc i just wanted to know that do they expire 60 minutes after i install the game or after 60 minutes of gameplay cuz if i download it and dont play for 60 minutes and it expires its a waste, so does it have to be 60 minutes of 'gameplay'? pls help its urgent.