Autodesk license borrowed from... gone! What now?

I had an AutoCAD license borrowed while upgrading the server to a new license file. Handing it back proved to be a problem because the lic had gone. A quick trip to the Autodesk Discussion Group revealed a few solutions;

• Wait – At the end of the Borrow period the orphan license will die. On next launch the application gets a new one from the new lic.
• Change the date on the machine to after the borrow period – This is a time warp version of “Wait”.
• Delete the borrow key from the registry – Like any registry edit approach this with extreme caution. Removing the key elapses the borrowed license allowing the new lic to function.