Alert User that Subscription Has expired /nearing expiry

Feedback from Customer
"You need to alert customers to the fact their subscription has expired so they can take immediate action to remedy the situation rather than just lock the book mid-flight with no warning, I wasted two hours of my life trying to figure out why your system wasn’t working. If it hadn’t happened in mid session I probably would have realized why the system wasn’t working. So you need an online alert that pops up when you login and the system is suspended, and you need a similar warning when a client is already logged in and your system kicks them out. Neither of these things happen currently."