A Chrome license allows your Chromebooks to be centrally managed via the Google Admin Console and with more control, security and customisation options than what is available without one.
Available from the 1st November 2018, Chrome licenses are able to be ordered at zero cost to the school

An MDM solution is the best way to manage school iPad's, Apple TV's & Mac OS devices. Mosyle gives you the ability to assign certain apps to different iPad's to be used in different learning spaces, for different age groups.

The best way to protect your network and Smart-Net server from being infected, is to educate all staff and students about not opening emails and files that you aren't sure about. Infection will come from PC's and if the machine is connected to the network it will infect the network.