Microsoft has said that after July 29th, it will be $129 to upgrade to Windows 10. But even if you don’t want to upgrade right now, you can still lock in free Windows 10 upgrade rights for life on each machine.

Windows 10 works differently than past versions of Windows. On most upgraded devices, it’s licensed a lot like iTunes. Windows 10 activates via Digital Entitlement, which forwards your machine’s MAC address and serial number (if available) up to the cloud, which Microsoft then hashes into an MD5 for your machine, of sorts.

When you reinstall Windows 10, you can skip entering a product key. Once Windows connects to the Internet, it will query the Digital Entitlement server, and send the same serial numbers back up. If the cloud recognizes that you have previously been licensed for Windows 10 on the machine – it will beam down the private product key, and complete activation. That’s it. No serial number required!

You can use this to your advantage. If you want to upgrade to Windows 10 later – after July 29th – you can install the Windows 10 upgrade right now, let it activate on the web… and then immediately downgrade back to Windows 7 or Windows 8.1.

The Windows 10 downgrade process is very reliable – mostly thanks to Windows 7, 8/8.1, and Windows 10 sharing the same partitioning and bootloaders. It’s just a simple matter of moving the Windows.old directory back into place, and properly stringing it back into the Windows bootloader. It’s more straightforward than you might think.

Also, you don’t have to re-download Windows 10 each time. Simply run the Windows 10 Media Creation Tool, and then plug the created USB flash drive into Windows 7/8/8.1, while it is running. Run the setup.exe, and follow the upgrade steps. Important: Do not boot off of the USB flash drive, only run it from inside Windows. If you try to upgrade by booting off of the flash drive – you won’t get upgrade rights, you won’t be able to downgrade, and you will have to reinstall Windows 7 or 8.1.

So folks, there you have it, even if you are a bitter-clinger to your Windows Media Center DVR (like me!), then you can keep it… and upgrade to Windows 10 down the road. You just have to run the Windows 10 installer, and make sure it activates, before July 29th. Then downgrade away.