Thanks guys. I quite like the idea of things being grandfathered after a significant change. My broadband ISP does this too when others don't, and I've stuck with them for nearly a decade now.
What I'm fishing for is if there is something in the terms and conditions that ensures that that would happen for people who have already purchased something. IB claim that they dropped hints that what happened this week was coming, but I don't keep an eye out for such things in random posts on theirs or anyone elses forums with an eagle eye (who has time?), and instead rely on things being as they are in the contract, and what turned out to be an incorrect assumption that I would be able to renew perpetually. I would never have forseen them completely changing the licensing model without notice and withdrawing the ability to renew support. If the potential is there for the same thing to happen with IPB sometime in the future, I'd just like to have it marked down on the appropriate side of the pros/cons column is all. Not asking for anything or otherwise making demands :)
