If you are Running Genuine Windows 8.1 of Windows 7

If you are running a legit licensed copy of Microsoft Windows, all you need to do is turn on updates. After your PC has automatically downloaded and installed all pending updates and you are done with restarting your PC, Windows 10 App will appear in your taskbar close to the clock region. Just tab the Widows icon and reserve your free upgrade. This offer is valid only till 29th July. For more details, check the link below

If you have a licensed Windows 8.1 or Windows 7 and are an Insider

If you are part of Windows Insider program, you are already running Windows 10 preview and probably know what you are doing. All insiders will get the stable build of Windows 10, but if after getting Windows 10, you opt out of pre-released builds, you will still retain your Windows 10. In case you run in an issue and have to format your PC and clean install Windows 10 from ISO, your copy of Windows 10 will still be genuine if you log-in from the same Microsoft account. Thus, if you are genuine Windows users and an Insider, you don’t have to worry about anything. If you had a license for Home version and are no running Pro version preview, you will still get to keep your Windows 10 Pro update.

If you don’t have a genuine Windows, you can still enjoy Windows 10

Yup, if you are using a non licensed Windows, you can still get Windows 10 Build, by joining Insider program.  After you Join Windows Insider program, you will get the latest pre-released builds for Windows 10. On 29th July, you will get full Windows 10 upgrade too. But you will have to continue testing Windows for Microsoft to be an eligible user.

New updates will be downloaded and updated to your device automatically and your PC will remain in beta state. You will have to bear with fresh bugs, which could lead to occasional crashes but you still get full Windows 10 functionality. If you opt of pre-release updates, your current Windows 10 build will expire after some time. Each Insider build update will come with an expiry date. If you are running Windows 10 Enterprise Preview Edition, you will not get free Windows 10 upgrade on 29th July, it is better that you reinstall the Preview with a Pro version to get Windows 10 update on 29th July. If you are not an Insider yet, head on to official Windows page for step by step instructions.

Wrap Up

So essentially, free Windows 10 upgrade is for genuine users. Microsoft wants maximum users to upgrade to Windows 10 as its based on a common app store for all platforms. They are targeting 1 Billion devices in three years and are mighty serious about it. Microsoft can’t afford Windows 10 not being a massive hit.