http://spywar2hncz3lkteymwfy7s6qxalsvw37gc4bywcf6v2b5hzjnwt5tad.onion/articles/bing.html
"Has Microsoft adopted and announced a specific retention period for a certain data type? For example, for Bing search queries, we de-identify stored queries by removing the entirety of the IP address after 6 months, and cookie IDs and other cross-session identifiers after 18 months."