Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
If you have a business (organization) subscription, you can add users in the admin center. Go to https://admin.microsoft.com . For details, have a look at https://learn.microsoft.com/en-us/microsoft-365/admin/add-users/add-users?view=o365-worldwide .
For consumer ("home use") products, certain licenses let you share the subscription with up to five family members. Read https://support.microsoft.com/en-us/office/share-your-microsoft-365-family-or-premium-subscription-b389b9ce-3ae3-4a82-9017-39d79972fcba .