Asking for a friend: I found out the guy I’ve been seeing has a history of addiction. Should I walk away now or give the relationship a shot?

Q: I found out that the guy I’ve been seeing for a couple of months has a history of addiction. He was very open about it and I didn’t expect it at all. I’ve never really gotten to know someone like this before, and I don’t really drink that much myself, let alone take any drugs. I wouldn’t have any interest in being around people off their heads, and he assures me that it is all in his past.