The description says Windows 10 Professional OS but it will not activate and there is no product key provided.  I have to purchase one for $199 when ad says the OS is already included.  It should be ready to activate.  Message says previous OS was updated without activating product like it was an illegal copy of the system.  UPDATE -- googled how to get product key and found MS Guides with step-by-step instructions for activating Windows 10 using command prompt.  Worked!