The answer is not completely correct, in CLISH there is a buffer that does survive logout and login, however there is a unclearity in there, sometimes I see commands that were issued on that system 5 sessions ago and sometimes the commands I get back from history are indeed from the previous session.
In expert mode all the history remembers is the current session, depending also on the default shell for the user, if that is bash than it will remember all commands even if you go into clish and return back to bash. However when you go into expert mode, it will only remember the commands that you issue untill you return to clish. the next time you go to expert the buffer is empty again.
Regards, Maarten