G'day
@Tanz
Have a look at the Ministry of Justice NZ
"How long does an Order last?" page. I assume its a Final Order (rather than an Interim Order which usually lasts until a set date, a particular event happens or the court says the Order stops)?
A Final Order:
"lasts until a child turns 16, unless it's a special case and the court has decided that the Order should continue after that".
So once they turn 16, the Final Order stops.
Hope that helps.