This is correct, six named activations per machine.
Now, assuming you have named activation... that machine has a 'fingerprint' that's tied into your AdobeID. Reformatting the hard drive would cause the activation server to notice and would delete one activation, and you'd only have five left. Unless you wait a year. After a year we automatically increase the count by 1 just to be nice.
Now, there is a procedure by which we can manually reset the machine activations in the odd situation where you might have used all six. for that you'd open a tech support case (for now... I hope to move that to Customer Service later this year)
Regards,
Bentley Wolfe
Senior Support Engineer, Flash/Flash Player/Digital Editions
Adobe