There used to be a pretty big business in US of reselling expensive software licenses (think AutoCad etc). I remember Autodesk trying to stop it and not being able to which brings us to the current day.

Of course now that everything is under pay as you go SaaS model, that's out of window.

Still in Europe it is legal (http://curia.europa.eu/juris/document/document.jsf?docid=124...) and people do resell mundane licenses such as Windows.