QuickBooks was installed with the wrong license number and / or product code.
If the amount of users are inaccurate, this can be due to using the single user license for installation instead of the correct Multi-User license.
Once the license and product information in QuickBooks is accurate, the amount of users will also be accurate.
QuickBooks (change the license number only):
Important: If the computer is not restarted it will still deliver the incorrect license number to the server when accessing the company file. So if QuickBooks is on a multi-user network with multiple seats, the computer will generate the error "You've exceeded the maximum number of users who can access the company file at one time."
Note: To avoid uninstalling and reinstalling the product, you must edit the qbregistration.dat file. Any typos or incorrect information saved in the qbregistration.dat file will prevent QuickBooks from opening properly after the edit.
Note: If old product number remains after performing the above steps:
If the license or product numbers have not changed after updating the qbregistration.dat file, it will be necessary to restart your computer and verify the information again. If they are still not updated after a reboot, you will need to perform a clean install of QuickBooks.