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 8, 8.1 (32 and 64 bit)
http://windows.microsoft.com/en-us/windows-8/create-reset-refresh-media
Alternative
http://windows.microsoft.com/en-US/windows-8/upgrade-product-key-only
Windows 8.1 Enterprise
http://www.microsoft.com/en-us/evalcenter/evaluate-windows-8-1-enterprise
Windows 10 (32 and 64 bit) and Enterprise
https://mkncreations.com/site/2015/09/download-legal-retail-windows-10-iso/
Windows 7 (32 and 64 bit)
https://mkncreations.com/site/2012/05/download-legal-retail-windows-7-iso/