The linked article doesn't mention tolerance at all? I don't believe there is any evidence out there to suggest that melatonin tolerance is a thing.
You're right! Edited the post...thanks for pointing this out was actually a mistake on my part the article was about incorrect dosage which was the point I wanted to make.
Ahh then yes that's a super valid point. I've seen shops sell 10mg per tablet. 0.5mg already does the trick for me.