What is international modeling license?

It's a common concept that people use to scam models. There is really no such thing as an international modeling license. The only document you'll have to deal with when modeling in other countries is a typical work visa. People will charge a lot of money for this so-called "license" when it is not necessary nor required. Anyone that approaches you about this should be avoided. Agency represented models will have their agents take care of all the travel oriented documents for the most part.