Contents
Introduction
This post is dedicated on showing how AutoCount USB Key Server works with AutoCount Backup Server in allowing users to authenticate their license.
Setup
On how to register the USB Key Server with the Backup Server, please navigate to this link AutoCount Backup Server
Local Client and Server Configuration Scenario

Local USB Key Server (SQL Server + Backup Server + USB Key Server in the same PC as the client) scenario
Remote Client and Server Configuration Scenario

A client trying to login to a database using a Remote USB Key Server (USB Key Server is separate from SQL Server and Backup Server)

Second client trying to login to another database on a different instance inside the same SQL server as the first client

Third client trying to login to a different database living in a different SQL Server but still using the same Remote USB Key Server as the first 2 clients to do so.
Conclusion
In conclusion, we can say that the AutoCount USB Key Server follows one rule that is a single USB Key Server can only allow SQL Servers in one PC (which may contain multiple instances and databases) to validate their license. As such if the deployment requires SQL Servers in multiple PCs to validate their licenses, the user will be required to purchase additional USB Key Server license in order to validate each PC.