School licenses : VPP, MDM,Apple School manager

It's the new Apple system for managing devices in educational institutions. It replaces the previously known VPP (Volume Purchase Program) system. If you haven't registered your institution yet, you can do so here

"MDM (Mobile Device Management) is a set of tools that allow you to manage all the devices in your center, applications, data, permissions, security profiles, and many other additional functions. Application management, licenses, and purchases are directly managed through these systems and allow, among other things, the revocation and reassignment of licenses for the center's applications."

This is the simplest way to obtain licenses for iDoceo. You will need a center account (an Apple ID), and from the App Store, on the iDoceo page, you can send licenses to teachers as 'gifts'