Printer printed pages count

The correct approach depends on what you need exactly. If you want to monitor system-wide page printing, there's a good discussion in this forum:
http://stackoverflow.com/questions/31983324/get-number-of-printed-pages-using-c-sharp-system-wide
If you want to do more than counting, such as capture the printed pages using a controlled print driver, then re-route them to any of the system printers, you can use this SDK:
https://goo.gl/BxV1kf
Nataraja