It has been reported that some MSDN and TechNet subscribers trying to activate Windows 7 Beta are unable to get a key generated. The TechNet team is aware of the issue and advise the following:
Windows 7 Beta has a built in 30 day grace period for installations before product keys are required. Customers with this issue can be instructed to download and install Windows 7 Beta without the product key and then check back later when this issue is resolved
Nothing to worry about or see here
What is Windows 7?