This is great from the perspective of contributing intellectual property back to the ecosystem. They are trying to balance the revenue aspect with growing an op

This is great from the perspective of contributing intellectual property back to the ecosystem. They are trying to balance the revenue aspect with growing an open community which benefits the product as a whole. My one concern is that the thrifty users will ride the expiration line, installing versions that don't cost money but which are outdated. I can see where that would be an acceptable tradeoff in many situations where the latest-and-greatest is not required. But from a security aspect I wonder if that also means that vulnerability fixes would only be available to the paying users. They are definitely worth paying for, no doubt; but would that then foster an ecosystem of not-really-patched installations out there? (Then again, that might not be that different from the current situation.)