Most likely you originally installed Key Ring from the Amazon app store. Unfortunately, you can't download updates from one store to the next. You can either wait for the updated version of Key Ring to be available in the amazon app store or you can uninstall Key Ring and then re-install the Android market version.
IMPORTANT: Make sure you have an account before you uninstall Key Ring! Having an account will allow you to restore your cards when you download the app again.