This is a pretty old bug - the launcher shows a relatively random timestamp for when the game time expires.
It may show it correctly when launched, but afterwards it just deviates, usually earlier. Right now for me it says 02.03 08.53, whereas the sub has been activated on 12.03 16:33.
I believe it is handled properly in-game, except maybe with long sessions, but I don’t stretch it for many years now.