[MicrosoftNorthstar]

Currently I dual-boot Windows 8.1 and Windows 10 Insider Preview on my Lenovo Yoga 2 Pro. I want to eventually delete both partitions and create one big partition to clean-install Windows 10 RTM. My question is, will I be able to successfully activate that Windows 10 with my 8.1-to-10 free upgrade rights if I delete and combine both partitions during setup? I mean, because we're not going to be given product keys for our free upgrade, right?

[6029KingStephen]

I think so, because your Lenovo will have your key stored in the BIOS, and Windows 10 reads it there.

But it seems from all I'm reading today that you must do the 8.1 to 10 upgrade process first, to update the key.

Once you have, to be on the safe side, you can extract the product key before you start, by using something like Belarc Advisor. Then if you're asked for the key (I was, on an older desktop) you have it to put in.

[Firipu]

I did the same thing on my surface Pro3.

My surface pro 3 partitions were totally FUBAR. I used diskpart clean in CMD to completely wipe everything. Then I reinstalled windows 10 directly from a recovery USB key (that you can download from the MS website). Just skip where they ask for a key, you can authenticate online when you're in windows.

Running a squeaky clean w10 build now.

[MicrosoftNorthstar]

you can authenticate online when you're in windows.

How does that work? I heard the product key is embedded into the motherboard/BIOS when you upgrade from Windows 7/8.1 and activation happens automatically. Or should I use a product key extractor and enter it in?

[Firipu]

It does so automatically if you have a valid w8/7/... key afaik. I skipped the part where I had to give in a key. When I booted in w10, my version was just genuine. Didn't have to do anything for it.