I downloaded Guilty Gear rev2 with the psn membership discount. My question is: if my subscription ever expires, will my digital download game be unusable? I only downloaded it because it has a discount of 19 dollars instead of 29 dollars.
I bought a digital game in playstation store and install it on my psn US account ps4. My question is: what if I decide to buy a new ps4 or let's say my ps4 broke and I need to buy a new one? Can I sign on my US account on my new ps4 and redownload my digital game copy in the library?
If you bought a game it's yours. Period. Only the free games you get for having a Plus membership will become unavailable once the membership expires. This also counts for the demo of Guilty Gear Rev2, which is only available for Plus members. And of course all online features will be unavailable as they require an active membership.
The game licenses are tied to your account. If you decide to get yourself a new PlayStation you can just sign in there and play your games as you'd normally do. If you want to get rid of your old console make sure to deactivate it as your primary device first. Doing so will save you a lot of headache.