tldr is that you can hide the button that asks for payment and it says “purchase immich” instead of “purchase liscence”
You’re keeping the project alive. You’re purchasing the ability to continue using a project that will sustain and continue to get updates and add features.
I agree it is not clear, but it’s also hard to say that in one or two words.
None of those things are true. Paying money is in no way guaranteeing the current developers will wake up wanting to maintain it tomorrow, nor am I purchasing access to an update service. It isn’t a purchase of anything and shouldn’t be framed as one. It’s a Contribution or a donation that gives nothing in return and saying it’s something else is dishonest.