Can the Windows 8.1 Preview be upgraded to the final release? [closed]

The same rules apply. If you upgrade Windows 8 to Windows 8.1 Preview you will have to reinstall all your desktop and Windows Store applications once you upgrade the Windows 8.1 Preview to Windows 8.1 RTM. Every single one of those FAQ applies to both Windows RT and Windows 8.

The important information is the following statement.

When you install subsequent editions of Windows 8.1 you'll be able to keep your personal files, but you'll need to reinstall your apps.

If upgrade to Windows 8.1 by using the Windows Store update or you use a Windows 8.1 RTM installation media you will keep all your personal files, settings, and installed applications. Any Windows Store applications in either case will be downloaded again and be updated as required.

There exists a possibility to upgrade from preview to final version of windows 8. This way is not supported by microsoft. So you should backup you data first, if anything went wrong.

The trick is to modify the version number of the installer its self. A full tutorial or possible tool can be found in this forum.