SUBOXONE ABUSE by BF

It seems I always find the men that either had a drug past or currently has one.... so this is one of those things.  My BF is a polysomnographer and had to take his certification/registration test this past week.  He took this before and failed, apparently this test is the hardest out there (maybe like the CMT LOL!!!)  Anyways, he had always taken these pills called Suboxone and I have transcribed this, but never looked into what it was.  These pills are about $60 for 2 of them!  He started taking them months ago, way before I knew him.  As far as I know they don't really alter him in anyway.  The pills just make him stay up and more alert.  These pills, however, are used for people coming off of heroin, among other things! 

So I said all that to say this... We moved in together on the 22nd of June and we haven't lived together long at all.  He PASSED his test on Thursday and he told me he would stop taking them or at least not so much since he wanted to start putting back money.  This morning I woke up and he wasn't there.  I called and he said that he was at the store and about to be back home.  He said he told my kids to tell me if I woke up.  I didn't think much of it until he was in the shower and his phone rang.  I looked to see who it was but I was too late.  I just so happened to be NOSEY and clicked onto his text messages.  I saw there a few that talked about getting the pills.... "Can I get 2 more?"  "I am really in a hurry and got to get back." 

So I knew right away that he just bought some.  Later he told me he was broke and might need to borrow $10 at the end of the week because he gets paid on Friday.  He never mentioned the pills at all.  So he doesn't want me to know he bought them.  I can't even say anything because I told him I wouldn't go into his phone anymore.  Has anyone had experience with this drug?  Should I really be worried about this or just let him do his thing?  I mean he pays all his bills on time and he usually does have extra money around.  Thanks guys!