The diagnostic criteria for addiction are whether the person can't stop doing the thing despite wanting to, and whether doing the thing causes problems. If they're stable-- whether on or off medication of any kind including opiates-- then the addiction is considered successfully managed.
Also, mental illnesses are never cured. They're managed, and the best possible outcome is stability over a lifetime. Typically stressors induce un-managed relapse, so staying on dope and keeping tolerance stable really is the best outcome for people living in adverse circumstances.