Bet Angel can be left alone to perform functions in your absence. However, It has not been designed to place bets or trade over the course of the day in your absence, unmanaged at the moment.
There are a number of oddities in the way Betfair and sports market work that make fully automated software difficult to administer without potential problems. Until such time arrives that we are able to confidently collect data from Betfair and other sources to manage these issues we will avoid making Bet Angel fully automated for certain types of activity. These types of activity can cause you to lose more than your account balance and are ruthlessly pursued by active market participants when they occur. We do hope to have a fully automated version at some point in the future but it will require a number of caveats, as all should, when you use it.