I signed up for it one day when I realized I'd left my credit card at home and needed to reload my SmarTrip card. I added $20 to the app and was able to get into the station to start my trip, but it would never scan at the exit. The station manager tried to help me figure it out, but in the end after many tries we got frustrated and they let me go through without paying. Sooo my app still says I have a trip going (from months ago at this point with no way to end it and start a new trip), and I bought a new physical card. Never again.