Hi and Welcome,
You cannot make your boyfriend stay clean. That's something he will have to do for himself.
My advice would be to make boundaries for yourself to take care of you, rather than making rules for your boyfriend. He's an adult and no adult likes to have rules to follow in his home. However, you can make a boundary such that if he brings his friends to your home, you will go out.
Please check out our Friends & Families forum on this message board.