Apps use User Defaults System to store your game progress.
Apps use Game Center Service.
Game Center Service tracks your best score(s) on a leaderboard
PLEASE READ AND UNDERSTAND THESE POLICIES:
http://www.apple.com/legal/internet-services/itunes/gamecenter/
Apps use IN-APP PURCHASES
PLEASE READ AND UNDERSTAND THESE POLICIES:
https://www.apple.com/legal/internet-services/itunes/us/terms.html