Super small feature request:

Adding the dates of the current billing cycle to the usage limit emails. This way I know how many more days there are in the cycle and if I should worry or not.

So instead of:

"You asked us to notify you when you reached $X of usage during the current billing cycle."

Something like:

"You asked us to notify you when you reached $X of usage during the current billing cycle. There are X days left in your current billing cycle (June 2nd to July 2nd)."