This wikiHow teaches you how to transfer your Windows 10 license and product key to a new computer. This will allow you to use your purchased copy of Windows Retail or Easy Upgrade on a new hard drive.
Steps

Step 1. Determine if your Windows 10 license can be transferred
There are some restrictions when transferring the license:
- If you upgraded from a previous version of Windows 7, 8, or 8.1, you will be able to transfer your license (but only once).
- If you have a full copy of Windows 10, you can transfer it as many times as you want.
- If you upgraded from a Windows 7, 8, or 8.1 OEM (pre-installed by the computer manufacturer), your Windows 10 license cannot be transferred.
- If you upgraded using Easy Upgrade to the Windows 10 Pro package from Windows 10, you will be able to transfer the license using Digital Licensing.

Step 2. Remove the license from the original computer
An easy way to do this is by uninstalling the product key. Here are the steps to follow:
- Press ⊞ Win + x.
- Click on Command Prompt (Run as administrator).
- Type slmgr.vbs / upk in the window.
- Press ↵ Enter. This will erase the Windows license, freeing it up for use on another computer.

Step 3. Install Windows on the new PC
When you install Windows, you will be asked to enter a product key. This is what you have to do:
- Select I don't have a product key (unless you bought Windows 10 from the store, in which case you can enter that product key right away).
- Select the version for which your license is.
- If you are transferring a Windows 7 Starter, Home Premium, or Windows 8.1 Core license, select Windows 10 Home.
- If you are transferring from Windows 7 Pro, Ultimate, or Windows 8.1 Pro, select Windows 10 Pro.
- Complete the installation. When Windows finishes installing, the computer will boot to the desktop.

Step 4. Press ⊞ Win + R
Do this when Windows finishes installing and you can use the desktop. This will open the dialog window.

Step 5. Type slui.exe and press ↵ Enter.
An activation wizard will open.

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

Step 7. Call the phone number and provide the facility ID
The phone agent will verify the product code and give you a confirmation number.

Step 8. Click Enter Confirmation ID to complete activation
Enter the confirmation number as directed by the onscreen instructions to activate Windows.