Here is a list of LEGAL retail copies of Windows 7, 8, 8.1 and 10 that you can download. None of those come with a cd key or any kind of activation software since that would be illegal:)
Windows 10 (32 and 64 bit)
http://www.microsoft.com/en-us/software-download/windows10
Windows 10 Enterprise
http://www.microsoft.com/en-us/evalcenter/evaluate-windows-10-enterprise
Windows 8, 8.1, Enterprise (32 and 64 bit)
https://mkncreations.com/site/2015/09/download-legal-retail-windows-8-iso/
Windows 7 (32 and 64 bit)
https://mkncreations.com/site/2012/05/download-legal-retail-windows-7-iso/