I may be well off on this, but it's surely the
downloading of the apps, not the storing of them, which is the problem, as its an internet usage issue. It has nothing to do with the phone's in built memory, as far as I can see. Zale's used 65% of his Internet allowance so far this month, and so nothing can be done to get that allowance back. You can, however, make sure the rest isn't used up too quickly.
Unless you meant the apps themselves were downloading things in the background, which could well be the case.
I reckon, from what you've said Zale, that one of your family members is using up more of the internet allowance than yourself (be that by downloading apps, streaming videos, whatever), so maybe chatting to them if you get any more messages from AT&T could be an option. 65% isn't too much, so you've still got plenty of allowance left for the month (almost 1GB, so you should be completely fine)