UsedSoft v. Oracle
The 2012 EU Court of Justice ruling that a downloaded software licence of unlimited duration may be resold, whatever the licence agreement says.
German company UsedSoft bought surplus Oracle licences from businesses and sold them on at a discount. Oracle pointed to its terms, which prohibited transfer, and went to a German court, which referred the question to Luxembourg (case C-128/11).
The court held that a download paid for once, for unlimited use, is a sale in all but name, so the distribution right is exhausted exactly as it would be for a disc. Updates delivered under a maintenance contract travel with it. Two conditions apply: the original buyer must render their own copy unusable, and a volume licence can't be split up. Subscriptions fall outside the ruling, which may go some way towards explaining why hardly anyone sells perpetual licences any more.