The new installation of an OS over an existing OS will delete the software license of your Largo. The license will be rendered useless forever. Please transfer your license to an eLicenser USB-key (i.e. Steinberg Key). These are available in most music stores for around 20 USD. It takes about 20 minutes to do it. Here’s a video about how to: http://www.youtube.com/watch?v=neld4Gdv8U0