The city of Amsterdam has stringent rules for renting out an apartment. You can only rent out the apartment where you are living for a maximum of 30 days per year, therefore you need a permit AND a registration number AND you have to let the city know in advance who will be your guests. This. is called Vakantieverhuur. see: https://www.amsterdam.nl/wonen-leefomgeving/wonen/vakantieverhuur/