I wanted my daughter to pay rent as well but changed my mind after seeing the cost for a suboxone doctor and the prescription. She was on our policy at the time but BCBS did not cover the meds, though we have prescription insurance. I let go of the rent idea but insisted she own her addiction and recovery, by paying for the doctor and meds.
It worked out really well for all of us. It compelled her to work more and FINALLY learn how to manage money. It was a slow process and took a few years, but she's doing really well and living on her own. Still recovering, one day at a time.