And on which PC do you plan to play for free with RDP ?

Your best bet is to ask your provider if you could get either a dynamic IP, or get your IP switched.
You can also try to uninstall gameforge client,
Remove c/user/your username/appdata/local/Gameforge4d folder
As well as the same folder in c:/program data/gamforge/Gameforge4d
As well as c:/program files x86/Gameforge/cache
And remove any entry containing "gameforge" from your registry.
Otherwise you are probably out of luck if you don't want to pay.
You could think about using 300$ trial money on Google cloud or Amazon cloud, to set up a proxy/VPN yourself. But i don't know if it will work.