Microsoft has today revealed that Windows 8 has sold over 100 million Windows 8 licenses since it's launch back in October 2012. This means it's been making on average 15 million sales per month, this is good. 100 million licenses in 6 months means that Windows 8 is on par with Windows 7, to some degree anyway.
Microsoft announced in January that Windows 8 had sold 60 million licenses since launch, this means sales for Windows 8 have dropped slightly since launch, from selling an average of 15 million per month to just 13 million. The drop was always coming, as the launch of Windows 8 came with a fantastic offer for $50, the OS is now $199.
Either way, 100 million sales puts it on par with Windows 7's sales within the first 6 months. 13 million sales per month for Windows 8 however, may turn out to be a problem in the long run. Microsoft need to do something to bump those sales back up, and they need to do it before the sun turns 'Blue'.