When discussing live tiles (also known as shell tiles) it is important to recognize the distinction between primary and secondary tiles. An app can have at most one primary tile, which can be pinned to the Start Experience by the user. In addition, an app can place multiple secondary tiles on the Start Experience, which can deep-link back to a specific area within the app. A primary tile is defined statically in the app’s WMAppManifest.xml file, whereas secondary tiles are created dynamically within code.
It is at the user’s discretion to pin an app to the Start Experience. You should not, therefore, rely on the presence of a particular tile on the Start Experience.
Windows Phone 8 supports three tile ...