I just made a thread regarding this and then I saw this one *sigh*. In short, yes, I think it is possible, but only under a certain set of circumstances which differ for everyone and every situation. For me, it's possible after a long enough period of abstinence to stop thinking about the drug in question. If I have to ask, the answer is probably no. I use drugs therapeutically for legitimate medical conditions, and also sometimes socially. It's rare that I use the substances I had problems with though. I have chronic but intermittent pain that can get very severe and I sometimes use opiates for that. I was also addicted to dxm and still use it a few times a year, but that's it. The thing is, I used to get intense cravings. Only when they stopped completely did I try using again. It was good but eh, idk, I need to have a reason to want to use it, like clearing my head or getting inside of it (same for all psychedelics though I was never addicted to any others). It's like I've reprogrammed my brain to get more pleasure from non drug sources, but somehow I've managed to curb my addiction issues almost entirely so behavioral addictions are no longer an issue either. If I used while actively craving drugs, it was a tease, and I relapsed every single time. It's pretty ironic, but only after I stop wanting certain drugs can I use them. I remember reading somewhere (totally paraphrasing here) that after a certain amount of time (about 2 months), the brain essentially collapses the dopamine pathways that form in response to a single pleasurable behavior, and then addiction to that particular thing is sort of "re-set" or something like that. With an addictive personality, there is usually an underlying problem with dopamine, so even if you manage to kick on addiction it'll be very easy to either relapse or find a different addiction. The solution is solving the underlying problem with dopamine. It has to do with the prefrontal cortex and the main symptom is lack of impulse control, which is why it's so easy to relapse or develop another addiction. Again, completely paraphrasing. Maybe someone else can weigh in on this. But it does make a lot of sense, the 2 month abstinence period definitely rings true for me and one thing that coincided with me getting over my addiction and impulse control issues was starting to treat my severe ADHD with stimulants, so dopamine upregulation might be the reason (I don't use stimulants daily but the positive effects last, so that's why I think it's dopamine upregulation).
TL;DR- yes, with a LOT of stipulations. Addiction is a disorder, substance addiction is just a symptom. You need to fix the disorder before you're safe to mess with drugs again. Even then, who knows? It's only been a few months, I have no idea if I'm permanently "fixed", I just know that I can use in moderation right now.