How to Restrict & Monitor Mobile Data Usage on Windows 8.1

Full article: http://www.howtogeek.com/187483/how-to-restrict-monitor-mobile-data-usage-on-windows-8.1/

Set a Connection as Metered

Let’s say you have a mobile data connection or a tethered smartphone connection. You may even be connected to a wired Internet connection with a harsh bandwidth limit. You can set this connection as metered to Windows knows you want to reduce bandwidth usage as much as possible. First, open the Wi-Fi panel by clicking the Wi-Fi icon in the system tray or opening the charms, tapping Settings, and tapping your wireless network icon. Right-click or long-press a network and select Set as metered connection to make it a metered connection.
The network you’re connected to will now be considered a metered connection by Windows. Windows sets mobile data connections to metered by default, but you’ll have to set Wi-Fi connections — for example, the Wi-Fi network created by a tethered smartphone — to metered on your own.
Note that this option doesn’t do much on its own. You’ll want to tweak the options below to really restrict data usage.

Track Data Usage

To track the bandwidth you’ve used on a network, right-click or long-press it in the same pane and select Show estimated data usage.
Windows is always tracking the amount of data you’re using, so if you enable this you’ll be able to immediately see your past data usage. You don’t even have to set a connection as metered to get this option.