According to a report on The Verge, 'M' was available through a bot on Facebook Messenger and it was available to only about 2,000 people.
'M' was first introduced in August 2015. The final day of the virtual assistant will be January 19.
"We launched this project to learn what people needed and expected of an assistant, and we learned a lot," Facebook told The Verge.
"We're taking these useful insights to power other AI projects at Facebook. We continue to be very pleased with the performance of 'M' suggestions in Messenger, powered by our learnings from this experiment."