gHacks posted Report: Windows 10 upgrade may turn retail OS into OEM version
A quote from the article:
Microsoft's free upgrade offer to Windows 10 stands until July 2016. Customers who work on genuine Windows 7 or Windows 8.1 systems may upgrade those systems to Microsoft's newest operating system Windows 10 free of charge.Report: Windows 10 upgrade may turn retail OS into OEM version @ gHacks