Have been running DraftSight quite happily for about a year on my MacBook Pro 17, 2.5 GHx i7, 16GB memory running Mac OSX 10.7.5.  DraftSight would't initialise at all so I removed it from the system then downloaded and reinstalled to get the same "This product is not licensed or has expired" message.  Have an inkling it may well be a corrupt plist file but can't find anything showing at all.  Any help gratefully appreciated!