When you reassign a Copilot for Microsoft 365 license from one user to another or to a different subscription within the same tenant, you may worry that chat transcripts, saved documents, and Copilot settings will disappear. Conversation history is stored in the user’s Microsoft 365 mailbox and OneDrive for Business, and a license change can disrupt access to that data if not handled correctly. This article explains how Copilot stores conversation history, why a license reassignment does not automatically delete that data, and the exact steps to reassign a license while preserving all past conversations.
Key Takeaways: Reassign Copilot License and Keep History
- Microsoft 365 admin center > Users > Active users > License and apps: Use this path to assign or remove Copilot licenses without affecting the user’s mailbox or OneDrive data.
- Exchange Online mailbox retention: Copilot conversation history is stored in the user’s mailbox as chat messages; removing the license does not delete the mailbox unless you delete the user account.
- OneDrive for Business data preservation: Copilot-generated documents and files remain in the user’s OneDrive even after the license is removed, provided the account is not deleted.
Why Conversation History Survives a License Reassignment
Copilot for Microsoft 365 stores conversation history in two primary locations: the user’s Exchange Online mailbox and their OneDrive for Business. When you chat with Copilot in Microsoft Teams, Outlook, or the Copilot pane in Word, each message is saved as a mail item in the user’s mailbox under a hidden folder called “CopilotChat.” These messages are not visible in the user’s regular inbox, but they are part of the mailbox data. Similarly, any files or documents Copilot generates, such as meeting summaries or draft emails, are saved to the user’s OneDrive for Business.
A license reassignment only changes the service plan assigned to the user. It does not delete the user’s mailbox or OneDrive. The mailbox and OneDrive remain intact as long as the user account exists in Microsoft Entra ID. If you remove the Copilot license and assign it to another user, the original user’s conversation history stays in their mailbox and OneDrive. However, the user will no longer be able to start new Copilot conversations or access the Copilot feature until a valid license is reassigned to them.
What Happens When You Delete the User Account
If you delete the user account entirely, the mailbox and OneDrive are also deleted after a 30-day grace period. During that grace period, you can restore the user account and recover the conversation history. After the grace period expires, the data is permanently lost. Therefore, to preserve conversation history, never delete the user account when reassigning a license. Instead, simply remove the Copilot license from the current user and assign it to the new user.
Steps to Reassign a Copilot License Without Losing History
Follow these steps in the Microsoft 365 admin center. You need Global Admin or Billing Admin permissions to perform license reassignments.
- Sign in to the Microsoft 365 admin center
Go to admin.microsoft.com and sign in with your admin credentials. In the left navigation, select Users and then Active users. - Select the user whose license you want to remove
Click the user’s display name to open their details panel. Do not check the box next to their name; click the name itself. - Go to the License and apps tab
In the user details panel, select the License and apps tab. You will see a list of all licenses assigned to this user. - Turn off the Copilot license
Find the Copilot for Microsoft 365 license in the list. Toggle the switch to the off position. A confirmation dialog may appear; click Save changes or Confirm. The user’s mailbox and OneDrive remain untouched. The user will lose access to Copilot within 30 minutes. - Assign the license to the new user
Go back to Active users and select the user who should receive the Copilot license. Open their details panel and go to License and apps. Toggle the Copilot for Microsoft 365 license to the on position. Click Save changes. - Verify the new user can access Copilot
Ask the new user to sign out and sign back in to Microsoft 365. They should see the Copilot icon in the app bar or the Copilot pane in supported apps. Their own conversation history will start fresh. The original user’s history remains in the original user’s mailbox and is not visible to the new user.
If the Original User Needs Access to Their Old Conversations
After the license is removed, the original user cannot view their Copilot conversation history in the Copilot pane. However, the data still exists in their mailbox. To let the original user see their old conversations, you have two options:
- Reassign a new Copilot license to the original user later. When the license is reapplied, the Copilot pane will load the existing mailbox data, and the old conversations will appear again. This works because the mailbox was never deleted.
- Export the mailbox data before removing the license. Use the Exchange admin center to perform a mailbox export to a PST file. The PST file will include the hidden CopilotChat folder. The user can then import the PST into their new mailbox if needed.
Common Pitfalls When Reassigning Copilot Licenses
Copilot Conversations Disappear After License Reassignment
If the original user reports that their Copilot conversation history is missing, the most likely cause is that the user account was deleted instead of just the license being removed. Check the Microsoft 365 admin center > Users > Deleted users. If the user appears there, restore the account within 30 days. After restoration, assign a Copilot license to the user, and the conversation history should return.
New User Cannot See the Original User’s History
This is expected behavior. Copilot conversation history is tied to the mailbox of the user who created it. When you assign a license to a different user, the new user sees only their own history. There is no built-in method to merge or transfer conversation history between users. If the original user’s history is needed by the new user, the original user must export their mailbox to PST, and the new user must import that PST into their own mailbox. However, this can cause data conflicts and is not recommended for routine license reassignments.
Copilot License Shows as Available but Cannot Be Assigned
If you have a limited number of Copilot licenses and try to assign one to a new user while the original user still has the license, the assignment will fail. You must first remove the license from the original user. Wait up to 30 minutes for the license to be released from the tenant’s pool. Then assign it to the new user. If the license still shows as unavailable, check the Billing > Licenses page to see how many licenses are in use and how many are available.
Copilot License Reassignment vs. User Deletion: Key Differences
| Item | Reassign License Only | Delete User Account |
|---|---|---|
| Conversation history preserved | Yes, in mailbox and OneDrive | No, lost after 30-day grace period |
| User can access Copilot after change | No, until new license assigned | No, account is gone |
| Mailbox remains | Yes | Deleted after 30 days |
| OneDrive files remain | Yes | Deleted after 30 days |
| Time to complete | 5 minutes | 30 days to final deletion |
Always choose license reassignment over user deletion when you need to keep conversation history. If you must delete a user, export their mailbox and OneDrive content first using the Microsoft 365 admin center or PowerShell.
You can now reassign a Copilot for Microsoft 365 license without losing any conversation history. The key action is to remove the license from the original user and assign it to the new user without deleting the user account. For long-term data retention, consider enabling Exchange Online litigation hold on mailboxes that contain important Copilot conversations, which preserves all mailbox data even after the license is removed.