Updates mean you have to buy app again!

Very disappointed. My sons teacher uses this and we bought it for my iPhone in the Fall but that app quit working, saying we arent using latest version and: update needed. There was no waiting update. My only option was to buy it again! I have the same phone (running the latest iOS) and Apple ID I did in the Fall. Why would you charge for updates? I dont recall being notified on my original purchase the app I was buying would be obsolete as soon as they came out with an update. Poor business practice.

Chelsea n Joes Mom about XtraMath