If metering is applied, team credit is shown (in hours and minutes) in the white box immediately to the right of the Menu button on the Team menu. This figure is updated every minute while you are in a team.
When your team credit falls below one hour the display text turns red and you are 'buzzed' each minute. If it runs out altogether you are automatically made to leave your team (and won't be able to join any more).
If team credit is not metered (as it would be while any team-related problems are fixed) then the string "(unmetered)" appears in the white box.