I usually turn off 3G data and connect only via wifi. In addition, when on 3G data, I use a firewall to allow only a few white-listed apps.
From time to time, I get presto license check fails when outside. If I stay with data connection off, after some time presto stops working, usually causing doggcatcher to crash. It only gets solved if I kill presto from the app manager.
I couldn't figure out the logic of the license check procedure, but I think that something is not being done right there. I get this verification problem at least once or twice a week in the past month or so.