Python GUI Application with tkinker and need watchdog process to keep the app running

I have a python tkinter gui based script where the app check for the rental status of a user from API based on his email address. This feature is already implemented. I just need a watchdog process implemented where if the rental status is inactive then the watchdog process kicks in and the user can't close the application till the rental status becomes active from the API upon checking from the app. The system will be locked and the user will only see our app locked page with logo. In addition to the watchdog process we need a push notification implemented where the user will be notified one day before his rental expiry period. We need the system to be an installable and there should be a password implemented when uninstalling the same.