After a bit of thought and following a couple of well represented points from Interspire partner reseller clients... I've opted to drop the requirement for customers to confirm their client status with Interspire.
In part this is due to the increasing frustration I've personally experienced trying to get the Interspire management to deal with critical issues in their products but mainly it's because there is no effective means of validating customers who have purchased their software legitimately through a third party.
That said, it will still be easier to get support if you can confirm your status with a simple PM to me (Websnail) on the Interspire forums once you've gotten all activated, etc...