The Graphisoft distributor your company bought the licenses from.
If you have access to the said PC but the license is not being used by it (i.e. you can't return it), then the only people that can release it back to your pool is Graphisoft.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10