Zen Account is a service made by Zen Inc. for Zen OS that allows people to keep backups of their games so that they can play it on multiple consoles. It also helps to make sure that only a certain person or group of people can install a certain update (For example, users that sign in to recieve beta updates).
While it is currently a working service, it's not implemented in Zen OS yet.
Zen Inc. said that "it might become an essential part of Zen OS in the near future".
The 6th of June 2016, Zen Inc. released a short video showing an early version of Zen Account running on Zen OS.
Zen Inc. also stated that as of now, all purchases are made free-of-chrage as there isn't a reliable way to store credit card information safely yet, but when Zen Account is released, it will be needed.