Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Sign in to the Microsoft account that you used to subscribe to Microsoft 365 and
(1) ensure that no more than one Microsoft account (for Microsoft 365 Personal) or six Microsoft accounts (for Microsoft 365 Family) have downloaded the apps; and
(2) ensure that each Microsoft account has no more than five open sessions with the apps.
In addition: Microsoft 365 Business is separate from the consumer version of Microsoft 365. For example, you cannot use a Microsoft account subscribed to Microsoft 365 Business to sign in to a Microsoft 365 consumer session.