Your product key is in the windows registry:
And the HKLM registry section is found at:
and you want the file "software"
From what I've seen, though, there is not an easy way to read a windows registry from Ubuntu.
Or another website I found suggested using wine to run a 3rd party registry editor to access the registry:
So, you could mount your windows partition and try one of these ideas. Someone else might have other ideas though...
Windows stores registry files in the "C:\Windows\System32\config" directory. While there do not seem to be any Linux utilities to open/edit these hives, there is still a solution. Of course -- using 3rd party Windows registry viewers/editors through WINE. There are many 3rd party programs that work similar to regedit, usually only allowing you to view registry hives and export them to REGEDIT4 format (.reg files used to modify the registry.) An example of one of these would be Regworks
. These programs can be used very easily to do many tasks.