There are actually two applications; a paid application and a free application. The base paid application is no longer updating as this is meant to be replaced by the free application, which instead has an option to process a one time payment to remove the brief advert at the beginning of the initial connection to the unit. When you're looking for the application in the App Store, just search "SlingPlayer Free" or "SlingPlayer"; this should bring up the proper options.
I hope this helps!
Sling Media Technical Support