Once additional licenses are purchased in the online store, the additional users are added to the existing serial key. To activate the additional licenses, run the Print2RDP Server and go to the License Information tab. Click License Upgrade and provide the same (original) serial number.
The Add-on license is mostly for customers with terminal server operating systems (Windows Server 2025/2022/2019/2016/2012 R2). If the user purchases an Add-on license, it means that the product can be used with different users on the same machine, unlike in the case of Additional licenses, where the license grants the user to use and register the product on different machines.
The registration process is described in the Registering Print2RDP section.