There is a very legitimate claim to copyright from the people photographed. If you claimed your own image was the most important thing in the photograph, or your art, or your club's 'image' etc etc etc. This is why model release forms exist. In the case of the OP, if they are not making profit from the photographs, then there is little point in anyone chasing copyright ownership. If they are selling images of people enjoying a night in a famous, or branded club, then they are profiting from the investment made by the club owners. The club owners could make a very viable claim for their share of the cash. e.g. People have paid €1,000 for a VIP table with champagne to be seen at a prestigious nightclub. If you (as the photographer) sell your photographs to them with an obvious "this is your night out in THIS very expensive nightclub called 'fabuloso fabulous spunking nightclib Ibiza dot com) then the owners of the club would rightfully make a claim after their investment, and would probably only allow Two professional photographers to operate within their premises on strict terms. In practice, everyone has a smartphone and everyone these days is the best photographer and owns all rights to their untold fame and wealth.