The Registration (Rego) or Vehicle Licence
Registration is something you have to pay every 3,6 or 12 month to be able to drive the car on NewZealands roads, like road tax in other countries. It is also an insurance for hospitals costs in case of an accident. The sticker in the left-bottom side of the windscreen tells you when it expires. When buying a car make sure it is still valid. You can renew your registration in any post office. Do it before the old one expires!
Links for more information on Registration: