X-chat is free, you can compile it yourself but it is a pita on windows, that's why a trial version was made http://hexchat.github.io/shareware.html
. I don't really understand how people get caught into downloading the trial version on windows though, Hexchat, Y-chat et al. are essentially just free pre-compiled binaries/patched versions of X-chat
You should consider using irssi or weechat with tmux/screen on a shell.