http://spywareitdaiuyfo2sqb5vsg7mek5cjabdr73luhnda57t2hyuzg7yyd.onion/articles/bing.html
Microsoft claims to store this information for an unlimited amount of time, but it claims that it will eventually anonymize this information in a process that takes 18 months to complete. "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."