Does Accessory to Treason charge exist?

Depends, in US (and now UK maybe too) I’d agree on yes, but in EU I wouldn’t know, since even selling 2nd hand licence is allowed and perfectly legal, and also any shit written in an EULA doesn’t make it legal no matter how small is written and how many times someone might have signed it.

Anyway for any EU citizen here just get in contact with your regional consumer centre for dispute resolution:

https://europa.eu/youreurope/citizens/consumers/consumers-dispute-resolution/informal-dispute-resolution/index_en.htm#shortcut-2-european-consumer-centres

I’d buy a dirty cheap Ubi game on Steam, so they won’t ever remove the account since it would be a fraud to Steam