Ubisoft did not state how long you can remain inactive before receiving the notice. If you play games by Ubisoft on PC, then you know the pain of having to deal with the company's own launcher every time you open them.
The age of digital gaming has brought along plenty of benefits, mainly quicker access to new games as well as saving space in the home. However, it also means that in many cases, we are beholden to the digital platform provider and their terms of service. Ubisoft recently confirmed that it will delete user accounts, as well as their purchased games if a user doesn't log in for a period of time.