As your conviction is 15 years ago (it is a significant benefit that it is more than 10 years ago), the question is whether you were sentenced to imprisonment for less than five years. If the sentence is for five years or more, you will be refused a resident visa. If the sentence is for less than five years, then you can be considered for a character waiver, which, if granted, will allow a resident visa to be considered. In considering the waiver the officer will consider factors, including the seriousness of the offense, any other offenses, how long ago this occurred, your connections to New Zealand and whether your potential contribution to New Zealand will be significant.
What due-diligence standards, such as prior criminal convictions, are there for investment immigrants to New Zealand?
I am from Ecuador and have a criminal conviction there from 15 years ago. But I have served my time and become a successful businessman. Can I immigrate to New Zealand through an investment? What kind of background checks are there?
In terms of the answer, what you are referring to relates to two things: character requirements for residence and the reputational side. In terms of the character requirements, since your convictions was 15 years ago, the only question is regarding the length of the sentence. If the sentence was longer than five years, then you would not meet the requirements. However, if it was shorter, you may. May is the operative word here, as immigration would need to conduct a character waiver. This leads us to the reputational, i.e., public security, public order or public interest, and the "fit and proper" person requirements. Therefore, while possible to apply, there is no guarantee of success