My understanding was (perhaps wrong?) that the “Mattermost Team Edition” is offered under the AGPL, and then the “Enterprise” Editions (starting with the “Entry Edition”) have additional restrictions (including the 10k message limit in the “Entry Edition” that everyone’s been talking about). They do a good job of hiding the “Team Edition” (it’s almost like the don’t really want to have to offer an open-source editions… 🤔), but it is there if you can find it. https://docs.mattermost.com/product-overview/editions-and-offerings.html#mattermost-team-edition

I’ve been running self-hosted Mattermost for a medium-sized academic org for a while now, and upgrades have always been a breeze, tbh (but I only use the version with open-source code only – the “Team Edition” --, not the Entry or any of the other Enterprise Editions, so that may be relevant).