Wìndows 10 full format without losing license

Unless you change to new hardware (motherboard), you should not need to do anything. You should be able to clean/reformat your harddisks and reinstall without an explicit windows 10 key (leave the windows key field empty during the install).

To be safe, I would recommend that you link your windows 10 product key with a Microsoft account. This should allow you to login with that account to re-verify your Windows 10, even if you have new hardware.

Step 1. Make sure you are using a Microsoft account:

Keep in mind that if you did not already have a Microsoft account, that your new login information will change to the email address/password associated with the Microsoft account.

Open "Settings"
Select "Accounts"
Select "Your info"
Select "Sign in with your Microsoft account instead" link.
Fill the information required
"Sign in" and follow the remaining instructions.

The next step is to verify that your microsoft account is associated with the windows key.

Once again, open "Settings".
Select "Update & security".
Select "Activation" on the left bar.

If everything is good, it should say next to Activation: "Windows is activated with a digital license linked to your Microsoft account".

When you now reformat your machine, simply login with your Microsoft account.

Step 2. Hardware Change

As the others have mentioned, if you have changed motherboard you would lose the "windows key" associated with it. That is why you will need to notify Microsoft about "Hardware change".

Select "Settings"
Select "Update & security"
Select "Activation" on the left side.
Select "Troubleshoot". It should say something about it failing to be activated on your device.
Select "I changed hardware on this device recently".
Login with your Microsoft account (if you haven't already).
Select the device you are using now, and select Activate

Sidenote: I have recently changed my own hardware (motherboard, CPU, GPU), and followed the steps above in order to keep using my same Windows 10 key. If for some reasons you had to take additional steps; please comment and let me know so I can update the step-by-step answer :)

Ivan Skodje

Posted 2018-06-01T02:09:03.357

Reputation: 36

Thank you. Does it work if I change to a new system (include a new motherboard)? I'm going to replace my entire system instead of replacing only HDD. – Khang Dinh Hoang – 2018-06-01T02:54:23.333

@KhangDinhHoang A new motherboard would come with its own license to Windows 10 (and the installation of Windows 10), you will run into activation issues, if you change the motherboard. Those issues can of course be solved but this answer doesn’t address those issues. – Ramhound – 2018-06-01T02:58:32.037

Thank you @Ramhound , I somehow forgot the second part; where you actually activate after hardware change :) – Ivan Skodje – 2018-06-02T05:26:49.447

I'm not 100% sure, but I think the Windows 10 license is stored in the BIOS. – Zackary supports Monica – 2018-06-01T02:21:11.147

It’s impossible to lose your Windows 10 license. If you have a HDD with bad sectors you should replace the HDD. Windows 10 license is not stored BIOS it’s stored in the ACPI table. A full format will not permanently solve your bad sector problem – Ramhound – 2018-06-01T02:25:01.620

if you want to check the whole disk for bad blocks, you can use chkdsk /R, rather than formatting the disk. – Frank Thomas – 2018-06-01T02:26:20.323

@FrankThomas yeah I did perform a chkdsk /R and it stuck at 33% for hours. – Khang Dinh Hoang – 2018-06-01T02:48:02.647

@Ramhound thank you, so I will replace my HDD – Khang Dinh Hoang – 2018-06-01T02:50:27.440