In accordance with the Advisory, a permit or license is needed in order to bring their own alcoholic beverages if the premise has more than a twenty person occupancy or if the premise is operating “for pecuniary gain”. For example, if the you must buy a ticket in order to enter this is “for pecuniary gain”.
As for providing alcoholic beverages to consumers free of cost, for instance, everybody (of legal drinking age) who attends an art gallery exhibition may get a glass of champagne if there is no fee to enter or any requirement to purchase.
If you must pay an entrance fee in order to obtain the glass of alcohol, it is considered a sale of alcohol. The premise must also require a permit or license if their premise has an occupancy of 20 or more. For example, a license or permit would be required if the art gallery in the previous case was giving away alcoholic beverages but had 20 or more guests.