Quick question, do you lose access to the game or do you just lose the ability to get the license for the game?
If you delete a ps+ game after downloading (and it has exited ps+) can you still download the game again?
Also when you stop paying for ps+ do you lose access to any games via it?
You lose the ability to play IGC games if you aren't subscribed, but they are always tied to your account, even after they are removed from the active promotion.
So for example, I downloaded inFamous 2 via PS+ last summer which has now been replaced by Dragon's Dogma, Uncharted 3 and XCOM. I can still go on the PS Store & download inFamous 2 via it's page or my account history freely, but only if I'm actively subscribed to PS+.
I don't think a game which has been part of PS+ has ever been removed from PSN outright, but if it's anything like XBL, I'd imagine you can always download stuff you've bought or been given via IGC.
Additionally, any game you buy which has an added PS+ discount is yours to keep forever, even outside of an active subscription.