Here's SmokeCounter in action:
The idea here is that you set yourself a daily maximum number of smokes and let the application keep track for you. Putting in the price per box (of 20? - sorry, I really am not sure!) will then also help motivate you to cut down by calculating how much you're spending each day on your habit; (right) the main SmokeCounter interface. Note that the application calculates when you're next 'allowed' a cigarette.
The simple Help screen; (right) note that your smoking stats can be exported to comma-separated-value text file for later analysis in Excel. There's also a dedicated stats page, for analysis in the application itself.
Oddly, this is listed as 'SmokeCounter English' in the Nokia Store and there are no other country variants, so perhaps other translations are coming - the author seems to be Italian(?) and there are some English typos. Might it not have been neater to have just the one application and then have a setting for 'Language' though?
You can buy SmokeCounter for the price of a couple of cigarettes £1 in the Nokia Store.