If I Download a Game from Playstation Store Will I Have It Forever?

i want to download/buy a game from play station store but if i do that how will i have the game for is it forever or for a set amount of days before the game removes itself from my ps3 please and ty

Suggestion:

if you download it for free using the playstation plus it will last an hour. if you use psn it would last forever.
and if you delete it you can always download it again with the same account, it would be in the bought area.