From what I have read, Windows 10 is a free upgrade for Windows 7 and Windows 8.1 during the first year after its initial release date. If you upgrade during that 1 year period then the licensing is for the life of the computer that you upgrade. If you wait until after t he 1 year period then you will need to pay a licensing fee. This is Microsoft's attempt to encourage everyone to upgrade so that they do not have the same situation with Windows 7 that they have with XP.
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