You probably want this - https://docs.moodle.org/33/en/Managing_authentication#Limit_concurrent_logins
But you might want this - https://moodle.org/plugins/view.php?plugin=auth_uniquelogin (although I'm not a big fan of database sessions)
You probably want this - https://docs.moodle.org/33/en/Managing_authentication#Limit_concurrent_logins
But you might want this - https://moodle.org/plugins/view.php?plugin=auth_uniquelogin (although I'm not a big fan of database sessions)