Have you ever downloaded the free version of an app because you're willing to deal with a bunch of ads, if it means saving 99 cents

Well your cheapness is costing you in the long run, so listen up.

A study out of the University of Southern California found that free versions of apps use 79 percent more network data than the paid versions–because of all the ads they stream.

That costs you around 1.7 cents every time you open the app, based on the average price of a data plan.

So, if you use a free app 59 times, you've now spent more than a dollar. If you use the free app every day for a year, it'll cost you $6.20, which is probably more than it would've cost you to buy the paid version.

That's not all. Free apps use 16 percent more energy, which can cost you almost an hour of battery life. Plus, they can slow down your phone, since they use 22 percent more memory.