Oephaelia what are you going to do with no money and no car? Please protect yourself. You're providing him with a means to carry on with his addiction by letting him live with you.
Can I suggest you set yourself up so there's no possibility of him stealing from you again? You won't be able to force him into treatment until he's ready, and that could take a long time. He's obviously worked out how to look after himself and get what he wants, if not legitimately, then by stealing. Just make sure he doesn't ruin your life as well as his, because no matter how much you love and worry about him, you're not going to be able to cure him.
Are you parents in the picture?