If you upgraded the old machine to W10 it's digital licence is based in it having had a licence for 8.1 from your key. Therefore that key is still 'in use' on the old machine. If that is the case then no, you are not entitled to use that key again on a second machine while the first machine is using it. My Computers. Meanwhile I got Windows 8 Pro retail license (actually I should have waited for pro license before free upgrade). My question is whether I can apply this License to Windows 8.1 directly or I need to reinstall Windows 8 again and use Pro license and then upgrade to Windows 8.1. Any way that I can revert back to Windows 8.1? My laptop originally came with Windows 8.1. I don't know how many resets, windows installations has it gone through, but is there a chance to revert back to it? 1. If you has 8.1, you went to 10 as a free upgrade, then 11. The 8.1 license became part of the final upgraded license. You can't use it This activation key ONLY WORKS WITH Windows 8.1 Pro. This activation key WILL NOT ACTIVATE Windows 8.1 OR Windows 8. No other Windows versions can be activated with this key. WIN 8.1 PRO MEDIA CENTER EDITION CAN NOT BE ACTIVATED WITH THIS KEY. WIN 8.1 PRO N CAN NOT BE ACTIVATED WITH THIS KEY. WIN 8.1 PRO K CAN NOT BE ACTIVATED WITH THIS KEY. EZITSOL USB Compatible Password Reset Recovery Boot Key Flash Drive | Compatible with Windows XP,Vista,7,8.1,10,11,Server | Remove Reset Recover login Password. 50. 50+ bought in past month. $2099. Save 10% with coupon. FREE delivery Mon, Dec 4 on $35 of items shipped by Amazon. Buy it with. This item: Microsoft Windows Professional 8.1 English 1 License. $19000. +. CORSAIR VENGEANCE DDR5 RAM 32GB (2x16GB) 5600MHz CL36 Intel XMP iCUE Compatible Computer Memory - Black (CMK32GX5M2B5600C36) $16969. +. App Vay Tiền.

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