I meant if you would for example try to open an external HTTP connection and it would be disallowed by the policy you would get a corresponding exception so if you caught it, you can react.
However you can programatically listen on ITPolicy cahnges by registering your own listener.
boolean appEnabled = ITPolicy.getBoolean(xxx8220;DemoAppEnabledxxx8221;, true);
you can check the values. Here it is a custom value, but maybe it also works with the standard policy values.