My laptop came with Windows Vista Business installed. It was upgraded by my employer to Windows Enterprise addition using their volume product key. I have subsequently left their employment and Windows is requesting an online activation. Must I purchase a Windows 7 Enterprise product key or can I upgrade my existing Windows Vista Business Product Key?
It seems that you will need to purchase a valid Windows 7 or 8 license. As you are no longer an employee at the company that provided the previous license, your current system is no longer "activated".
You should be able to purchase an upgrade license and bring your system current.