Microsoft may have officially the free upgrade period months ago, but still seem to sponsor other free upgrade methods.
http://www.notebookcheck.net/Users-might-still-be-able-to-upgrade-to-Windows-10-free-of-charge.190908.0.html
Another way is through the assistive technologies section on windows 10. The process is the same as the upgrade offer last year, and you dont need to burn isos