For those who have OEM Commercial User Types through Esri, there isn't a process in place to have notifications sent when the end of the year subscription is near. We lost access to our OEM user types due to no notification of their date of needed renewal and no early warning system or communication is in place for that.
Please look into creating an early warning system or communication for ArcGIS Online admins who work with OEM user types for OEM user type renewal timelines.
