Oracle got a major setback in the European Court of Justice in a lawsuit to a company reselling otherwise legally acquired software licences. The Court of Justice was asked by a German court for guidance, and their recommendations are usually followed (since it basically means that if the issue were to be taken higher, it would be the expected outcome).
The European Court of Justice on Tuesday ruled that used software licenses may generally be resold by individuals or companies. The Luxembourg-based court thus sided with the German firm UsedSoft in a protracted legal battle with US software giant Oracle.
The ruling made it clear that trade in used software was permissible even if the software had not been shipped on a physical medium such as a CD or DVD, but had been digitally downloaded from the Internet.
The ruling, available here, also makes it clear that the original seller is obligated to offer a download of the software to the new owner.
An additional ZDNet article:
Oracle, which makes a vast proportion of its revenues from maintenance agreements as well, had tried to argue that it does not sell software as such, only licences. However, the court effectively backed up Bot's opinion that this was an "artificial distinction".
Whether this means that a storefront such as Steam are required to make it possible to deactivate a program and sell the product key is probably way too early to tell, but in effect, the "we sell licences" excuse should no longer work in Europe.