This is quoted from this thread...http://www.arturia.com/evolution/smf/index.php?topic=13025.msg112861#msg112861
"Once you license is downloaded you cannot erase it actually.
So, to transfer your license on a second computer, or simply allow its use on several computers (one at a time), you will need an USB-eLicenser dongle (the famous "Steinberg Key", sold separately), and to transfer the license onto by a simple drag-and-drop in the eLicenser Control Center.
This little video show the simple process:
USB-eLicenser dongles are also used by editors such as Steinberg or Korg. If you don't own any, you may either purchase one from our online store:
...or from any decent music shop, especially Steinberg or Korg resellers."