Hello and welcome to the Autodesk Community!
According to our records, you only have the free single seat educational licenses of Autodesk Inventor associated to your name. If you have a different 8 seat purchased Autodesk Inventor license you should contact the Activation and Registration department for assistance on a manual activation:
1. Visit http://knowledge.autodesk.com/contactus
2. Select “Activation & Registration” or “License Management”
3. Select appropriate subtopics from the pull-down menus
4. Select “I Still Need Help” if you need personal assistance
There you will be able to chat with a live representative or submit an email if all chat agents are busy. However, if you are trying to install the single seat free licenses on 8 computers that won't work. The free licenses are single seats only and only have one automated activation available.
If you have any other questions please let us know. Thanks!