The 31-year-old was reported missing on Monday, September 21, in the Clarence area after she did not arrive at work.
Her worried family said it was out of character for the keen adventurer not to keep in touch with family.
Ewings lived alone in a rented house at Clarence, 60km north of Kaikoura.
She was last seen just before dusk on Sunday, September 20, but failed to show up at work at a beekeeping business just 400m from her house the following morning.
"While we are no longer actively searching for Melissa, we will review any new information that is brought to our attention," said police's Marlborough area prevention manager Peter Payne.
"Every missing persons enquiry is treated on a case-by-case basis and a decision about when to suspend a search involves a number of factors, including the areas able to be searched, evidence located and other lines of enquiry being exhausted.
"We want to acknowledge how difficult the past few weeks have been for Melissa's family, friends and colleagues and we will continue to keep an open mind as to what has happened to her.
"We also want to thank the search and rescue teams and volunteers that have helped search for Melissa."
