Most venues will have information on what is required of the vendors and who to contact for permits.
Out here, if you are working outside of your licensed area, you submit a temporary vendor application along with the fees to the health dept where the event is being held, at least two weeks prior to the event, they will inspect the day of the event.
If you pass, you work, if not, you go home if you can't correct the problem..
Example..... Instructions Application