Recently, I had a client using Office 365 Enterprise E3 and Enterprise Mobile + Security E3 licenses. After the trial version of O365 Enterprise E3 expired, the client decided to go for Office 365 Business Premium to save money while using Office 365 services that were needed. At last, Azure RMS is already covered in EMS E3. So far, everything seems to be fine but switching to Office 365 Business Premium was a bad idea because the previous configured Azure Information Protection did not work properly combined with the new Office 365 Business Premium licenses after license assignments.
What happened:
The Azure RMS license is covered by EMS E3 as already mentioned but nevertheless you will only see AIP labels in Word, Excel etc. but no labels with protection enabled. The issue is that Office 365 ProPlus license is required to integrate and to make visible the Azure RMS features like labels with protection.
By right-clicking on a file it gives you the option to encrypt the file using labels with protection but for sure you want to make use of this in the Office application directly.
How the issue was resolved:
All Office 365 Business Premium licenses were recalled and replaced by Office 365 Enterprise E3 including Office 365 ProPlus and everything worked fine again once it was assigned to the affected business users.