People were selling XIV registration codes?

[Jacost]

I assume this does not apply in the EU, where it is legal to sell property you own (the right to use the unused serial number to obtain a game, not the right to use the service). Unless there is a special clause somewhere.

Thing is, games aren't property you own. What you're buying is a licence to use the software, not the software itself, and said license is non-transferable.