Then you set up a bot that logs on channel (there are even dedicated services for that). Or use a client on a remote server to which you then connect (e.g. weechat).

It works mostly like this: I have a problem, let's say with QML, I log into their IRC server, ask the question and it is fixed. Then I don't work with QML for a month or two, then I remember that during the session two months ago they also linked to some cool tool but I can't find the link anymore (for example), I would like to be able to go back there and just search for my conversation. In the meantime I wasn't in that chanel or logged in into that server.

But perhaps I'm wanting too much from a chat system.