How to decrease user plan usage based on service usage?

I'm dealing with a Steam farming hour system, I can start the farm via a method from client instance, like

const user = new SteamUser()
user.logOn()

const user = new SteamUser()
user.logOn()

At this point, the client starts the farming. How can I count the user service usage? Like a setInterval? Pub/sub? Observers?

If this service is in a different server than the application one? How should I do this communication?