Usages

public class RateExample : MonoBehaviour
{
        private void Start()
        {
            // Init at start
            AppStore.Init();
        }

        // Call this to request rating view, if fail it will go directly to store page
        public void Rate()
        {
#if UNITY_IPHONE || UNITY_IOS
            AppStore.Review("YOUR_APP_STORE_ID_HERE");
#else
            AppStore.Review();
#endif
        }
		
	public void OpenStore()
	{
            AppStore.OpenStore();
	}
}

If you got missing class error with classes bellow on device (Android), add this to your proguard file.

-keep class com.google.android.play.core.** { *; }