My son has an account our home computer (manjaro kde) as a standard user. He runs steam for gaming and I have a time keeper on his account so he does not spend his whole life gaming. He has many classes at home now because of the COVID second wave and I have created another account for him for his school work and so that it does not use his gaming time while attending online classes. The problem is of course that he can now run steam from this new account too and gets around the time keeper.
How do I prevent a particular user from running particular programs (steam in this particular case)?