I have mixed feelings about the locking up the medicine idea.
On the one hand, if my spouse was on Xanax that she kept locked and I really wanted some, a lock would not stop me. I would find the keys, or something.
On the other hand, having peace of mind is important for me too. So I can appreciate the idea as well.
From what I've read, sounds like the problem is honesty. A lock wouldn't make me want to be more honest.
Whatever you decide to do, I hope things work for you. I can't imagine what it would be like to live with a dishonest spouse (*someone like I used to be*).