I would to ask for help in finding a counter to monitor the number of printouts. I am planning to put up a photo printing business and this will be used for operational control.
Unless some software for monitoring turns up quickly, set up a simple inventory control of your paper stock. I keep track of the consumption of each paper size. I don't do so much, so my paper is sorted to small batches. A simple pick ticket is under each batch. When the batch is depleted, the ticket is logged into a file. You could choose whatever quantities best fit your consumption rates.