Hi guys. how can I monetize my rustdesk servers? like, imagine I tell client X to pay 1$/month for using my server, how can I authenticate users? (prevent others from using the server so only people who are paying can use).

CONTEXT: I live in a country with very limited internet (like china) so using public servers is not good. I would also have to be able to maintain the costs of the server. so this is not illegal and not unethical.