Although "not supported" : it still works on 9.0 but the PMPro settings cannot be changed in manager.
A work around is to create two User Right tables in the Manager 8.1 and copy them into the 9.0 config, one without the Pro activated and one with the Pro option activated.
If a user on 9.0 needs a Pro version just copy the user rights with the Pro option activated to that user.
Obviously you need PMPro licenses.
From 9.1 and higher the PmPro cannot connect to the IP Office, the link is blocked.