In Windows 8, some Metro Apps display Live Tile notification updates, delivering information either periodically or in real-time. The same information can also be displayed on your lock screen by the apps of your choice.
However, you may want to limit data usage for these apps, to avoid reaching your data plan cap before it resets. Here is how you can do that:
1. The options you need to access are only made available if you set your wireless network connection as metered. This is the first step to do, when you have a small data plan. Besides access to the option of limiting data usage for tile updates, setting your wireless connection as metered makes Windows conserve bandwidth, delaying all unnecessary transfers until you can use an unmetered connection.
Read here how to set your wireless network as a metered connection, and go through the necessary steps.
2. Go to the Start Screen. Open the Charms Bar (Win + C or hold the mouse/finger in the top-right or bottom-right corner of the screen). Click/tap on the Settings Charm to access the Start Screen Settings.
3. Click/tap on Tiles. In the Data Used for Tile Updates section there is a dropdown menu from where you can select how much MB of data can be used for tile updates. You can choose from the following values: 50/100/200/300/400 MB or Unlimited. There is no option for entering a custom value, so hopefully one of the available ones will suit your needs.