Regulatory describes something that holds you to the rules. Detention is regulatory, as are other kinds of punishments. When your mom tells you not to run in the house, she’s being regulatory.
You’ll notice most of the word regulate is in regulatory. That’s because when something is regulatory, it’s regulated. You also might be reminded of the word regular. Things that are regulatory, like being forced to stay in for recess, are intended to keep things regular — no breaking rules, no breaking laws, no breaking at all. Things that are regulatory are meant to keep you from falling out of line.