Every time I make an estore purchase, I log it in a spreadsheet. I then check that spreadsheet regularly and follow up things that haven't posted about 6 weeks later (returns window as previously stated).
It is a shame you have to do this, but you really do. Also read all the small print and the like before making a purchase. Apple for instance weren't giving points on newly released devices.
You should be able to treat it as fire and forget, but you just can't.