The Elite HRV app can be found on both Google Play and the Apple App Store. If your phone or tablet supports Bluetooth 4.0, and has either Android 4.3+ or iOS 7+, then it is likely compatible with Elite HRV.
Why discharge your heart rate monitor? Sometimes the heart rate monitor can retain some residual charge that causes interference in the signal. These steps will remove any residual charge and allow for a cleaner signal. Depending on the monitor, this may have to be done every once in a while.