If you are on a certain data plan on your mobile provider, and don't want to exceed it, you can set data usage warning and a limit which can help you save some of your money.
At any given time you can reset your Nexus 4 smartphone to the factory default settings, meaning you will bring your phone back to the same state as it was on a day when you took it out of the box.
If for some reason your Android powered smartphone does not perform as good as it used to, or you want to sell it I suggest you to bring it to its original factory state.
