If, for example, your app or add-in requires a login/password, you must give Microsoft a pre-existing working login for testing purposes.
Your app experience must not prompt a user to disclose the credentials of a Microsoft identity (for example, Office 365 or Microsoft Azure Organizational Account, Microsoft Account, or Windows Domain Account) except through Microsoft approved OAuth flow, where your app is authorized to act on behalf of the user.
If you make changes to your app or add-in such that the functionality does not match the description, you must resubmit your app or add-in.
Users must not be required to read support content to perform basic operations.
For more information, see Best practices for developing Office Add-ins.
Failure to do so will make you responsible for refund liability towards your customers.
Apps and add-ins may convert from free to subscription pricing.
You can determine the length of time that the free account remains active (indefinitely or for a limited amount of time); however, if the user’s account expires, you cannot show any UI, text, or links to the user to indicate that they need to pay.