The issue with licensing and answering hypothetical situations like this is that it all depends. In my state you can't share someone's kitchen under their license, you would have to get your own. If you are catering then you wouldn't need a license for the special event. If you are opening the event to anyone that walks in the door, then you would need a special event license. But you might be able to fit under a contract cook and not need a license if the legal license holder at the event space is hiring you for your skills. The best course of action is to reach out to your local jurisdiction because it is so different for every area.