You need to upgrade from windows 7 to windows 10 in order to make your key fit for Windows 10. You can reinstall windows 7 and then upgrade to Windows 10.
or you can join the insider program.

also try extend or shrink the destination partition

You can use diskpart.exe to delete that partition, and then convert the disk to GPT. If you are not familiar with diskpart, try a free partition manager software. you can find many of then in the...