This article explains how to transfer your Windows 10 license to another computer. This allows you to use the copy of Windows you already purchased on a new hard drive.
Steps

Step 1. Find out if your Windows 10 license can be transferred
There are some restrictions that limit license transfers:
- If you have upgraded a purchased copy of Windows 7, 8, or 8.1, you can transfer your license (but only once).
- If you have a purchased full copy of Windows 10, you can transfer it as many times as you like.
- If you upgraded a copy of Windows 7, 8, or 8.1 pre-installed by your computer manufacturer, you can't transfer the Windows 10 license.
- If you upgraded Windows 10 using the Easy Upgrade feature of the Windows 10 Pro package, you can transfer the digital license you received.

Step 2. Remove the license from the original computer
An easy way to do this is to uninstall the product key. Here's how to do it:
- Press ⊞ Win + x.
- Click on Command promp (administrator).
- Type slmgr.vbs / upk in the command prompt.
- Hit enter. This removes the license from Windows, freeing it for use on another system.

Step 3. Install Windows on the new PC
When you install Windows, you will be asked to enter the product key. Here's how to do it:
- Select "I don't have a product key" (if you didn't buy Windows 10 in-store, in case you should enter your product key now).
-
Select the OS version for your license.
- If you are transferring a Windows 7 Starter, Home Premium, or Windows 8.1 Core license, select Windows 10 Home.
- If you are transferring a Windows 7 Pro, Ultimate, or Windows 8.1 Pro license, select Windows 10 Pro.
- Complete the installation. Once the Windows installation is finished, your computer desktop will appear.

Step 4. Press ⊞ Win + R
Do this when Windows has been installed and the desktop appears. The Run window will open.

Step 5. Type slui.exe and press Enter.
The Activation Wizard will open.

Step 6. Select your country and click Next
A phone number and installation ID will appear on the screen.

Step 7. Call the phone number and provide the installation ID
The operator on the phone will check the product code and give you a confirmation number.

Step 8. Click Enter Confirmation ID to complete the installation
Enter the confirmation code as directed by the on-screen instructions to activate Windows.