The days left shown on the Live Tile is incorrect or no longer updating?
This happens after the app hasn’t been launched for two weeks or more. The Windows Phone OS actually disables the part of the app that updates what gets shown on the Live Tile after 14 days of the app not being launched by the user. The fix for this is coming in an update soon; it will change from showing the days left to a request to the user to launch the app to re-enable the Live Tile updates. In the meantime, try to launch the app at least once every couple of weeks and it’ll stay up to date always.