Radmin is commercial, proprietary software. It does not operate on an open-source or freeware model.
Here are the proper ways to write it:
Radmin Server 3.5.2 offers a range of features, including: License Code For Radmin Server 3.5.2
If your Radmin Server is installed on a computer that cannot connect to the internet — such as computers in closed networks, secure environments, or air-gapped systems — offline activation is the solution. Radmin is commercial, proprietary software
Do you require a solution or a self-hosted/local network setup? Radmin is commercial
Designed for service providers who need to connect to third-party client computers.