Try upgrading an activated Windows 7 to Windows 10. Once upgraded and activated you can then do a clean install of Windows 10.
I have a Vostro 3250. It came with Windows 7 Pro installed  with the option to upgrade to Windows 10.  I recently tried to install the Windows 10 upgrade in a new ssd, using these steps:  a) I installed the "Dell OS Recovery tool" b) I opened it and chose "Advanced Recovery"c) I chose "Windows 10 without Support Assist"d) I replace the original disk with the ssd.e) I changed to "UEFI mode and SecureBoot on"f) I completed the installationNOTE: It didn't ask me for my LICENSE KEY. My problem is that Windows is not activated. May you please help me to activate it?Thanks in advance.  
Windows 10 upgrade problem