• Go to the Download Windows 10 page and click the Download tool now button.
• Once the download finishes, run the Media Creation Tool.
• If the tool is already on the PC you're wanting to upgrade, choose the Upgrade this PC now option and enjoy your free upgrade to Windows 10. If not, go to the next step.
• If the tool is not on the PC you're wanting to upgrade, choose the Create installation media for another PC option.
• Follow the prompts and then choose whether you want to put the installation files on a USB flash drive or ISO file. Transfer whichever option you chose to the PC you want to upgrade.

Users report they are not being asked for a product key, assuming this is performed on a valid Windows 7 or Windows 8/8.1 PC. Once the upgrade is complete, you can head to Settings > Update & Security > Activation to confirm it worked without a hitch. Alternatively, if you already installed Windows 10 and still need to validate it, as long as you have access to your old Windows 7 or 8 key, you can just head to the same section and select Change product key, then plug in your old key.