I would do that the other way around. If you wanna spend something you gotta hold your finger down and thus punish your behavior. For me it seems that the app punishes you with waiting time when you wanna save money.
What about the privacy issues of keychain-stored identifiers (iOS 7)?
For example Facebook stays signed in across its apps, even if they are deleted. So they could just put an Ad identifier inside the keychain storage and have an unremovable tracking identifier. An user can't remove that on his own. Even if he signs out, they can keep the identifier in the keychain for tracking.
I'm curious why I couldn't find any info on that in the internet?