Microsoft is warning customers that are using the Windows 8.1 Preview and Windows RT 8.1 Preview s to upgrade to the real thing before those preview licenses expire on 15 January 2014.
Customers will not have the right to use the platform after that date, and will likely lose unsaved data
Note: As with any Preview update, only data and accounts will be migrated; all apps will need to be reinstalled
Customers who installed Windows 8.1 Preview on top of Windows 8 will be able to upgrade via the Windows Store. However, those who tried the “beta” by installing it on top of Windows 7 will either need to restore the operating system, or shell out up to $200 for the Windows 8.1 upgrade.
Customers using Windows XP and Windows Vista cannot upgrade directly to Windows 8.1. They will first need to upgrade to Windows 8, and then perform the upgrade to the latest version via the Windows Store