Microsoft's Windows 8 upgrade promotion really is ending on January 31

Existing Windows licensees have until January 31 to get Windows 8 Pro for $39.99. After that, upgrade prices are on the rise.

When Microsoft announced last year a "limited time offer" for Windows 8 upgrade pricing , some thought — or at least hoped — that the discounted price might be indefinite.

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Microsoft officials announced on January 18 that this will not be the case.

After January 31, the $39.99 upgrade price will end. Starting February 1, the Windows 8 upgrade (from previous Windows home/consumer SKUs) will cost $119.99. The Windows 8 Pro upgrade will cost $199.99.

Currently, Microsoft is charging $39.99 for an upgrade license to Windows 8 Pro from Windows XP, Windows Vista, or Windows 7.

Testers who've been working with Windows 8 preview builds also have been eligible for the $39.99 upgrade price . The Windows 8 preview builds (Developer Preview, Consumer Preview, and Release Preview) all expired earlier this week. After that time, users with those builds will notice that Windows 8 will restart every hour "until they've installed a released (RTM) version of Windows," a Microsoft spokesperson confirmed earlier this week.

Here's information on what users upgrading from XP, Vista, and Windows 7 can expect to migrate (and not) when upgrading to Windows 8.