Many parents here have used Melatonin quite successfully and without addiction. But ... when it comes to addiction, something doesn't have to be physically addicting to be come psychologically addicting, and the later remains a risk. In the parent child relationship you have the ability to keep the use sparse enough that your child doesn't get to that, but you do have to make sure YOU don't get overly reliant. So ... if you have a tendency towards psychological addiction, or have seen tendency in your child, be aware of the possible issue and see what you can do to keep it from surfacing. I confess, psychological addiction is something I find myself prone to, so that is why I bring it up.
_________________
Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).