GTR KeyGo users can their smartcards on Metrobus and Brighton & Hove buses in the main towns they run in and it works similar to NX West Midlands in that you pay the maximum fare for journeys in that town for one journey and for 2 or more journeys then you pay the day ticket price. Overnight batch processing calculates how much you need to pay and that is deducted from your stored credit card. If you have also used trains then you might only need to pay the Plusbus price for the bus journeys. Unfortunately there is also a short hop fare so you cannot use KeyGo for those trips unless you don't mind paying more.