How to implement internet statistics?

Question

Computer networks

Good afternoon. There was such a question about the Internet provider.
Each Internet provider has statistics pages to which each is assigned to a client and is given a Login / Password to enter the statistics when connecting to the Internet.
So, if you go to the statistics page where all the information about the client is written, how much money is in the account, what tariff is connected, all information about accommodation. So I'm interested in how the provider itself transmits information about how much money each client has in the account, each has its own tariff, how to create such an algorithm?