Eh, most airlines going for satellite WiFi aren't doing it out of the goodness of their hearts - they're doing it because the unit economics make sense. There are exceptions like JetBlue who offer it for "free" though.
Make it easy to purchase WiFi access and just about everyone will click that box. Once on the plane, just have the customer scan their boarding pass or something to enable the service. Laptop users could be accommodated by entering the usual 6-character confirmation code that they already use for everything else.