Android N Data Saver
We can't all have unlimited data plans, which is why Google added a "data saver" to Nougat. If you choose, data saver will limit background data usage on cellular networks. Meaning when you aren't on WiFi apps will be more cautious with your data.
You can enable data saver for individual apps too, which is a nice touch. Only limiting the apps you're worried about. Data Saver goes even further by telling apps to use less data while in the background or foreground. That last one is designed to let developers control battery usage in addition to the software doing it too. This may even improve battery life in certain scenarios. And finally, data saver can be setup any day you'd like. So set it for the end of the month around the 24th when you know you may be close to the limit.