Right before I submitted the app (a second time) for review, I decided to ask the user if they wanted to upgrade to the full version every time they saved a bill...I forgot to also remove the buy button on the main menu, when a purchase was made in that particular instance. The user still got the full version, but as you can imagine, the presence of the buy button made it look as if the features were still unlocked.
I'm of course working on an update to fix those..and add a few new features.
Although, testing with some apps right now it appears both ways works, but I have noticed that apps also generally include an edit button that then lets me select multiple items and do a particular action on them.
MAKE SURE APP RINGS HOME EVERY TIME IT OPENS TO SEE IF THERE IS
ANY URGENT MESSAGES I'D LIKE TO TELL ALL MY USERS.
I don't care the slightest if it's something Apple doesn't want you to do, or wants you to do over notification center, just do yourself a favor and create a direct channel between yourself and the customers (so that you can send them a message whenever you felt like).If you had such channel, you could've told them (after an apology for the inconvenience it's caused) how to remove bills, and that you're working on the next version, and the buy button was a bug, and avoid 1-2 star reviews, and sell much much more (no one buys/download a 1.5 star app).
Just to be clear, did you want this app to appear in the AppStore?
A real world example of how this can ruin your rating:
I use a text editor on OS X called 'Mellel'[1], which is available both in Mac App Store and as a direct purchase. It's excellent and supports RTL languages (Persian, in my case) better than any other text editor. There was a bug on OS X 10.7.4 that caused the cursor to disappear. It was a simple bug and the developers issued a notification to all non-App Store customers (they obviously have their emails) on how to remedy this issue, but it took them like 10 days to update the app on MAS, causing a few negative reviews.
[1]: http://itunes.apple.com/us/app/mellel/id415467848?mt=12