@On Rustdesk server software seems free to me. It is open source and free of charge. If you need service because you don’t succeed installing it, that service will not be free. I cannot see any limitation to use rustdesk with their or own relay servers, but I have not understood yet the difference the company defines between managed and unmanaged users. I guess it depends on your usage if you hit any hidden limits in the free plan, if they exist.
Alternatives for GUI remote control include VNC. But I’d tunnel it through SSH because it’s weakly encrypted, at least the last time I checked it.
If you find any evidence for your assumptions on rustdesk.com or experience, please let us know.
