Update is not applicable to your computer
UPDATE IS NOT APPLICABLE TO YOUR COMPUTER FOR FREE
That is, if your computer is running Windows 8, then your computer has eligible for free updates and it is possible to upgrade to Windows 8.1 from Windows 8 without losing files and installed applications.
While PC users who use Windows 7 and earlier will be forced to purchase a copy of Windows 8.1, the latest version of Windows 8.1 is available for free download for existing Windows 8 users.