Why SSPR runs without licenses

We have some confusing data on how licensing for users in an on-prem AD may affect SSPR and password writeback on Azure AD.

MS documentation does not spell it out well, but it suggests that to use the feature users need to licensed.  But in practice, both in our own test environments and in customer environments, we have worked with in the wild we have found that only one of the Global admins for the account will need to licensed.