Nice, and correct answer. The solution is and probably will be to just put up a second box in the event of a failure and then replace the primary in 90 days.
I don't think that would be very economical. You would need to purchase twice the amount of licenses you need. i dont think that would actually work anyways. I believe a license client can only communicate with one license server.
Just setup a second MAG2600, you don't have to license it at all. If your primary license server dies just import the entire configuration from the failed server into the backup and it will run as a licenses server for 90 days. This assumes you are regularly backing up/archiving your configuration from your primary license server.
Not a single license server, but 2 license servers in an active/passive scenerio. Specifically to see if one license server dies we can with small effort fail it over.