Applies to: Microsoft Teams.
Desktop
In Teams, you can discover and continue a previous conversation. Regardless of how many times you’ve talked to that person, it’s all in one location.
Find an old message
All your old messages are saved, and you can filter for them (and people, chats, and files) using the command box at the top of your screen. Select your desired conversation to resume.
To search for an attachment, check in the Files tab above your search results. You can select Filter 
to narrow your results.
View saved messages
To check your saved messages, pick your profile picture at the top of the app, then press Saved.