Microsoft released the free public preview version of Windows 8.1 in late June 2013, but Wednesday anyone who still has that build of the OS installed on their PCs needs to upgrade to the final shipping build, or they will have some issues with running their computer afterwards.
As we have previously reported, the Public Preview will expire on January 15th. In a post on Microsoft's support page, it states that if the preview version is not uninstalled after that date, "you'll see the following notification every time you sign in. After January 15, 2014, your PC will also restart every 2 hours and you will lose any unsaved data."
People who got the preview build of Windows 8.1 from the Windows Store can simply download and install the final version from the storefront for free. If the preview version was installed via booting from ISO media, users can still download the final version from the Windows Store but they still need to purchase a license and product key in order to activate it. The support page also offers help to users who might have installed the preview build on a PC that previously had Windows 7, Vista, or XP.