The FriendNet client is stored in a single executable, and can be updated simply by replacing the file.
If the client is currently running (in the background or not), shut it down by clicking the red button on the top right
of the web UI. Once you have done that, simply replace the old friendnet-client.exe (or friendnet-client on
other platforms) with the new one. You can now run the client again to start the new version.
Next: Yggdrasil Support