It depends on your monthly data limit. Using the apps themselves won't result in an increase in your VZW bill, but you have to remember that the longer you use an app, the more data it uses. If, for example, you are paying for 4gb of data per month, any amount of data over that limit will be billed extra. Those two apps you mentioned aren't the only things that will result in increased data usage, of course. A good way to monitor your data usage and to check what your limit is is to download the My Verizon app from the Play Store. I use it all the time to check how much data I've used in throughout the month thus far. If I get close to my limit (of 4gb), I turn off data on my phone.