Can You Leave New Zealand and Come Back Again?
An NZeTA can generally be used for multiple trips while it remains valid.
But again, this is where it is important not to confuse multiple entry with permission to live in New Zealand indefinitely.
New Zealand can examine how much time you have already spent in the country.
Under the visa-waiver rules, you can generally spend up to six months in New Zealand in any 12-month period.
If you have already spent six months in New Zealand during that period, you may need to apply for a Visitor Visa before travelling again.
So to say, Repeatedly entering the country to maintain what is effectively a continuous long-term stay is not the same as being a genuine short-term visitor.