Vac

Just wondering, say i used a hack a few days ago but stopped using it [still am, all theoretical] and it got detected after i stopped using it, would vac still ban be by knowing i used it before it was detected?

If u stopped using it before it got detected then your fine.

And on a side note can VAC be updated without your knowledge while in game or would it ask you to update the game.

If you stopped using it, deleted it from your system, and removed all traces of it, there is no chance of you getting VAC banned for having an unknown file on your computer.