Expense Log is a ready-made tab where you log what the business spends and see it month by month: the total, the biggest category, a split by category and every entry, newest first.
It also adds a Monthly expense summary task that writes the month's totals by category and its five biggest expenses into your Brain whenever you run it. The task is added switched off and only reads your log - turn it on from the Tasks tab when you are ready.
A few sample expenses are included so you can see how it works, and one click removes them.