American equivalent of UK regulatory license

[snoopy]

Does anyone know what the American equivalent is of something called a license to trade / regulatory license in the UK?

I am going around and around with someone in the UK trying to ascertain what exactly they need from me.

The closest thing seems to be a tax id number?

 

[Aceon6]

Tax ID + registration in the state(s) that require it. For example, anyone selling insurance in Massachusetts must be registered with the Commonwealth’s Division of insurance.