OUSA chief executive Debbie Downs said she hoped the association had played a role in normalising drug checking for MDMA and other drugs among young people.
Once she had understood the prevalence of recreational MDMA-like drugs such as molly, or ecstasy, among student-aged people, she had decided that an anti-drug campaign would be fruitless.
The best role for the OUSA was to try to reduce drug harm, Downs said.
"It's a very, very different world to 20, 25 years ago when I might have been at a party somewhere," she said.
"As older adults, as parents, sometimes we forget that.
"It's as common as having a beer."
Know Your Stuff NZ Dunedin regional and South Island manager Finn Boyle said it was difficult to say whether there had been an increased uptake of testing since the temporary legislation was passed in December, but testing results this summer had been concerning.
More than two-thirds of the presumed MDMA tested this month in Dunedin was a potentially dangerous substitute.
Only about 30 per cent of drugs presumed to be MDMA in Dunedin were MDMA.
More often than not the drugs were a substitute drug, typically from the cathinone family.
And nearly half of the supposed MDMA tested was the new, and potentially dangerous, drug eutylone.
Eutylone was first identified in New Zealand at an OUSA event in 2018, Boyle said.
About 80 per cent of the drugs Know Your Stuff NZ volunteers were testing was presumed to be MDMA, but testing LSD and ketamine was also common.
The drug-checking company had always been public about its purpose and its results, but it had to be quiet about the events it attended, he said.
With the new legislation, it could now be very clear about where it was testing, Boyle said.
But a stigma remained around clients and the testers themselves.
Some people held the view Know Your Stuff NZ volunteers were at events to encourage drug use, but Boyle said the organisation was concerned with informed decision-making.
The least risky drug was no drug at all, he said.
"But we accept that often people do choose to use drugs and so we are here to try to reduce the harms and risks involved with that behaviour."
When the temporary legislation was passed in December, Health Minister Andrew Little said the Government would develop and consult on regulations to provide a long-term solution.
There was evidence that drug harm-reduction initiatives had not resulted in more drug use but kept people safer, he said.