With registration labels no longer required on windscreens it is not easy to check when the rego is due. Miss that and you could be driving as an unregistered, uninsured vehicle. One work-around is to gum a small typed note to the windscreen in front of the driver: 'CAR REGO DUE ON xx/xx/20xx'.
A good tip, although state governments will remind you so they can get their cash.