If you don't have Windows 10 Professional already installed, we recommend you first download and install it from here: https://www.microsoft.com/software-download/windows10
To Activate Windows 10 Professional with Retail Key follow this:
1.Click Start, Go to Settings
2.Select Update and Security
3.Click on Activation Tab located on the left side
4.Click on Activate or Change Product Key
5.Enter the License Key you received after purchase
6.Done, now your Windows is fully activated and you will have access to Premium features
If you encounter any issues or received any error during the activation process, please contact us at support@premiumcdkeys.com or Contact Us page.
Buy a genuine Windows 10 Professional - Retail License Key from here: https://www.premiumcdkeys.com/products/microsoft-windows-10-professional-retail-key