I've shared PS plus with my friend since yesterday, which is not illegal in itself, but if you shared a game that cost money you can be blocked, then my question comes: how long will you be blocked if you have shared a game ( I'm just curious)
So me and my friends have been playing games for 1 1/2 years and none of us have been banned until now
Theoretically it is not allowed, but in practice you will not be banned for it. In any case, I'm not aware of anything in that direction.