Yes, what bulu said.
If you haven't any wish to travel outside NZ, your Residence would continue to be valid indefinitely - it will only expire if the travel conditions run out with you OUTSIDE NZ. The travel conditions let you leave and return without restriction for two years from the date of validation. After that, what happens depends on what you have done in the course of those two years. You may be eligible for Permanent Residence (PR), which will allow you to travel in and out freely for ever.
http://www.immigration.govt.nz/migra...quirements.htm Or if not that, yet, you might get a variation of travel conditions, as mentioned in the sidebar on that linked page.