In short, if you want to use M360 on multiple computers, simultaneously. Like if you have more than one shops with different locations or if you run a big service/repair centre where you are running M360 on a few computers at the same time.
With multiple licences, the user you registered first will become the "manager" of your account. You can invite "operators", who have limited access on the dashboard. The work history in the M360 application shared between the manager and all operators, and you can even filter entries by the username as well.