What does it say on your friend's visa? Does it have any conditions on it?
Section 49(1) allows a variety of conditions to be placed upon a visa, in a variety of situations. The most common use of it, however, is for when an applicant has a job offer in NZ counting for part of the points for their ITA. The Residence visa is then given on the condition that the applicant takes up that specific skilled job within (usually) three months of arrival in NZ, and works in that job for at least three months - when they show INZ that they have done that and are still in the job, they are then given Residence without any conditions.
But the sticker in any Resident's passport clearly shows any conditions upon the Residence.