In the BigBlueButton plugin, you can enable Activity Completion in Moodle.
Activity Completion requires that the BigBlueButton server send live events back to Moodle, and Moodle is configured to receive those live events.
To configure Moodle, login as Administrator and in the Plugin Settings, and enable Register live events. This will request the BigBlueButton server to call back to Moodle with detailed events.
By default, the BigBlueButton 2.5 servers (and above) have a post_event callback script located in
/usr/local/bigbluebutton/core/scripts/post_events/post_events_analytics_callback.rb
that will automatically run as part of the processing of a recording that contains a request for callback.
However, if your Moodle server is behind a restrictive firewall, the callback might not reach the server. When you enable Register live events, do a test recording (and set the threshold for attendance at 1 minute) to ensure that the callback occurred.