The Psychoactive Substances Act passed through parliament in July but police gave service stations, bottle stores and dairies 28 days to strip the products off their shelves.
Specialty stores had the same period to apply for an interim licence to sell the goods.
Now the law in is full effect any store owners caught selling the drugs illegally face a fine of up to $40,000 and up to three months in jail nu skin product
A company found to be importing or manufacturing could be fined up to $500,000, with individuals spending up to two years behind bars.
Sales are restricted to those aged 18 and over, nuskin group
advertising is banned outside stores and the products have strict labelling rules.
In the first month, both government and police reported a dramatic reduction in the number of retailers selling legal highs.
Residents of some towns, including the small Waikato community of Putaruru, banded together to ensure all its stores no longer sold the products.
New Zealand follows Australia's New South Wales which instituted a statewide ban on the drugs following the death of teenager Henry Kwan, nu skin hong kong
who jumped to his death from a balcony after taking a drug bought online.