As you may all well know Microsoft ended its free Windows 10 upgrade program on 07/29/16. But it seems this is not the end of story yet. There are still some ways you could upgrade your Windows installation for free.
Use assistive technologies
Even though the general free upgrade offer ended on July 29, Microsoft still offers the free upgrade possibility to Windows 10 if you are using assistive technologies such as the Magnifier, On Screen Keyboard or Narrator. In that case you can go to this page and click the link to download a little application that starts the free upgrade for you. Even though the application does not check if you really use assisitive technologies you are not encouraged to use it if you don’t.
Make a clean Windows 10 (1511) installation
If you have your Windows 7/8/8.1 key on hand, you can “upgrade” to Windows 10 for free if you do a clean install of your system with a Windows 10 (1511) ISO. Since this is not a real upgrade I recommend you to backup all your data first, so that you can re-install all applications after you are on Windows 10. You can download the official ISO files from Microsofts “Download Windows 10” homepage, just make sure to pick the right one for your system and license. After the clean installation you should be able to activate your system with your original Windows 7/8/8.1 key.
Use the Anniversary Update application
On Microsofts Windows 10 update history website you can download a little Application named “Windows10upgrade28084.exe”. If you start it under Windows 7/8/8.1 after some time you will be asked for a license key to proceed. Now, somehow someone found out, that if you rename the application to “Windows10upgrade24074.exe” you won’t be asked for any key during the upgrade process. Obviously you are not encouraged to do so, but you wouldn’t do it anyway, would you?