If he's still into drugs at this stage of his life, then you should steer clearly away from people like him or you'll pay the steep price of living and learning the hard way.
The drugs will come first with blokes like this and their significant other will always come 2nd or 3rd, depending on who his fantasy girl of the week is.
You still have your whole life ahead of you, so please try not to waste it on him.
Thanks for providing some context to all of the winks. There was clearly a lot more involved than just winking going on. Frankly, I'm suprised that you even had to ask what the winks were all about. It sounds to me that he's a bit bold toward you from him still using drugs at his age. He's lost some brain cells, don't you think?
You'll learn that some guys just never grow up.
Maybe you're drinking and have lost some of your ability to discriminate good guys from bad?
I may be wrong and I'm sorry to be so blunt, but you asked for advice and now I'm giving you the best that I have to offer.
Liking him as a friend is one thing, but as serious marriage material?
He's way past his prime and still doing drugs while you won't be in your prime until you're 27 or 28.
Please tell us that you're only kidding...