Overage transactions free plan

I have the free plan with 15,000 transactions per month, currently in the website it seems that my app has requested more than 50,000 transactions this month, however, I have not received any email regarding that I've reached the 80% nor the 90% (I have already rechecked it) and the app seems to be working fine, and the free plan seems to not consider overages according to the https://developer.mapquest.com/overages. Why is the app still working? Should I revoke the key? Will the extra transactions have any cost?