As soon as copyright protection expires, you can use a work any way you want. Once the protection expires, the work is common property, meaning it belongs to the public domain and is free to use. This is why your friend can not only play Frédéric Chopin’s Raindrop Prelude for themselves at home, but also in front of an audience in the Zurich Tonhalle. But be careful – even if the work itself is no longer protected by copyright, the 1975 recording of the work by Maurizio Pollini for Deutsche Grammophon, for example, is still protected by related rights.

You are also not permitted to modify a work that is no longer protected – if you paint a moustache on Leonardo da Vinci’s Mona Lisa, you are distorting the work, but not infringing any copyright. Of course, you are not allowed to paint over the original in the Louvre in Paris – that would be damaging the Louvre’s property. You can, however, paint to your heart’s content on the Mona Lisa post cards sold in the museum shop and distribute them.