Since the 29th of July 2015, Windows 7 and 8 users have the ability to upgrade their system to Windows 10. But what is needed to benefit from the FREE UPGRADE? Well Microsoft has already give the necessary explanations about this matter and here below are the main points:
Microsoft primarily wants to attract Windows 7, Windows 8 and 8.1 users by offering them free upgrade. To qualify for the upgrade, you must have valid license key. By cons, if you are using Windows XP or Vista, then you will need to purchase Windows 10. This free offer expires on the 29th of July 2016. The free transition to Windows 10 is only valid for a one year after its official release date. Passed this period, you will need to pay between 80 and 200 € for Windows 10. The update is permanent as long as it has been done with a valid license key. If you have switched to Windows 10 during the free one year period, then you can keep using the new OS as long as you want.
Windows 10 is not only about upgrading your operating system; you are upgrading your license at the same time. You can create a bootable installation DVD or USB and reinstall Windows 10 on your device at any moment (even after the free one year period).
Learn more in this article: How to Create a Windows 10 Installation DVD or USB Key
It should be noted that Windows 10 also gives you a one month delay (after its installation) to rollback to your previous OS provided that you have a valid license key.
Learn more in this article: Windows 10 - How to Recover Your System after a Failed Update