I found that, the definition of user: A user is an individual that has access to application you make; in other words an end-user. We do not charge for anonymous (not signed-in) users accessing your applications. We also do not charge for developers making apps on our platform. In current situation, my customer has a licensed application. They want me to maintain that app and I want to know that : do I have to pay to participate in the maintenance of that application?