To retrieve your Windows 10 activation key, you can try the following methods:

1. Check the Settings App: Go to Settings > Update & Security > Activation. If your Windows is activated, you might see the activation status and the last five characters of your product key.
2. Using Command Prompt: You can run the following command in Command Prompt to view the last five digits of your product key:

      wmic path softwarelicensingservice get OA3xOriginalProductKey
   

   This command may show the original product key if it is stored in the BIOS/UEFI.
3. Look for a Physical Copy: If you purchased a physical copy of Windows 10, the activation key is usually found on a sticker inside the box or on the card that came with it.
4. Email Confirmation: If you purchased Windows 10 online, check your email for a confirmation message that may contain your activation key.
5. Contact Microsoft Support: If you are unable to find your key through the above methods, consider reaching out to Microsoft Support for assistance.

Keep in mind that if your device came with Windows pre-installed, the key may be embedded in the firmware, and you might not have direct access to it.

If the product key window does not open, enter the key from Activation settings instead:

1. Select Start.
2. Go to Settings > Update & Security > Activation.
3. Select Change product key.
4. Enter the 25-character original product key.
5. Follow the on-screen steps.

If Windows was previously activated on that same device and the license is linked to the hardware or Microsoft account, it may activate automatically after connecting to the internet and signing in.

If this is a new PC or a different motherboard, Windows 10 needs a valid product key for activation.

If the PC was repaired or rebuilt and a different edition of Windows was installed, reinstall the original version of Windows and enter the original product key.

If the key was already used on another PC, activation may fail. In that case, a separate product key or copy of Windows is required for each PC.

References:

• Windows 10
• Why can't I activate Windows? | Microsoft Support

Hello,

If you're looking for a Windows 10 product key, we can't provide that for you.

However, with that said, we can give you a link to purchase a Windows 10/11 product key that will allow you to activate your copy of Windows 10 Pro. That can be found at https://www.microsoft.com/en-us/d/windows-11-pro/dg7gmgf0d8h4. It costs $199 in the US but depending on your location, it can fluctuate due to currency differences. If you would like, I can link a different location for you.

Hope this helps.