What incentive does he have to take care of himself when you are doing everything for him? Why should he rock that boat? He has a place to live, food, heat, laundry service, taxi, phone service, and everything else and all he has to do is sit around and do dope. You are making everything so easy for him. Of course, you could also be killing him.
Nothing changes if nothing changes. He's not going to change until you do, and maybe not even then. That's his business. Try doing something different instead of continuing to do the same stuff you've been doing for years. That hasn't really been working out for anyone but him.