Note he said for previous versions. So someone could have activated their Win7 in a row until he hit a block, then wait 90 days and try again. I assume people on this forum have been through everything you can possibly do, so maybe someone did this.
Nope, the system goes like this: for XP/Vista/Win7 - Retail/COEM, on start-up windows checks on 10 devices, if 7 or more is the same like last time(7 yes's), then windows considers it's the same machine, less than that, it asks you to reactivate. But MS has to consider a user may need to repair/upgrade some items from time to time, e.g., you may replace the graphic card, then later do a format and re-install(which changes the drive ID), then you get only 8 yes's; so in 120 days(I think it's not 90 days, couldn't remember exactly), windows would re-set the records and accept the new changes, and you get another 10 yes's over the 2 new changes.