The fact that Microsoft does not enforce licensing requirements for many of the features in Office 365 is something we often discuss here on the MTC. This time however, one specific feature will start enforcing license requirements, so make sure you are well aware of the changes. Namely, Shared and resource mailboxes in Exchange Online will now be created with the 50GB quota as mentioned in the documentation. If you need to go over that limit, you will need to apply an Exchange Online Plan 2 license to the user object corresponding to the mailbox.
Technically, the licensing model is not changing, what's changing is the fact that Microsoft will now actually enforce those licensing requirements. Read the full article here: https://blogs.technet.microsoft.com/exchange/2018/06/21/correcting-shared-mailbox-provisioning-and-s...
