I think that the answer to your question you can find at the link:
there is a fragment:
"... Note: If you are running an OEM version of Windows, the migration may fail. VMware cannot support OEM copies of Windows migrated to virtual machines as this is a violation of Microsoft licensing conditions. If you purchased your computer with Windows pre-installed, you are most likely running an OEM version of Windows. To check whether you are running an OEM version, see the Microsoft Knowledge Base article 310104. ..."
Regards
Mark