Further investigation led to the retail licence being cancelled.
"Without the assistance of this concerned member of the public that retailer might well have continued to break the law."
Since the Act took effect in July there has been a significant reduction in the range, availability and access to the products.
The number of retail outlets selling legal highs has dropped by 95 per cent from an estimated three to four thousand to less than 170 interim licensed premises around the country.
There are currently no outlets in Wairarapa with an interim licence to sell legal highs.
Mr McClay said there was also further evidence that the Act was working.
There were fewer people with health issues related to these products going into hospital emergency departments, according to DHB reporting.
Calls to the National Poisons Centre had almost halved - there were 63 calls in August, and only 34 in September.
Dairies, convenience and grocery stores, service stations, and liquor outlets are banned from selling psychoactive substances.
The hotline number is 0800 789 652.