Well, I do not know, how this is handled in the Russia, Spain, Italy (the counrtries where I guess the app. were). May they have some flat rate or may (as it is possible in my country) you can chose to pay a special amount of traffic.
Apart from this they need to handle the traffic on their site or to be precise on their server. Because of the different locations of the app, I reckon they (RLC) just rent some space on local data centers. As far as I know you often have to pay for the traffic additonal, besides the rented space. So it should be a matter of money.
Well, I'm not a professional neither. Just got a little into this topic. And I'm sorry for my bad Englisch, it is not my first language.