Tiles Transactions monitoring

Hi,

We are developing a new mapping feature for our existing (desktop) software. We are looking to use the map tiles provided by your 'open mapquest' project (ie tiles from http://otile[1..4].mqcdn.com/tiles/1.0.0/map). I understand that there is a usage limit of 15,000 transactions per month, I am wondering how best to monitor how many transactions our customers are generating?    We would like to know if we are getting close to exceeding the number so we could migrate to another plan before our customers would potentailly be blocked.  (We have an AppKey but I think that will only work if we were to access via the Leaflet plugin)

thanks