I hear the evaluation version organ sound even after the program has accepted the registration codes

From N-Track Wiki

Make sure that a 16 bit format is selected in the dialog boxes that appears clicking on the hammer button on the recording and playback vumeters. Try to restore the program's default settings: load the program, open the Preferences dialog box and click on the 'Revert preferences to default settings'. If you've registered the 16 bit version, the program will play the nagging sound when used for 24 bit recording or playback. If you're using Asio drivers with a 24 bit soundcard with the program registered in 16 bit mode please note that Asio drivers dictate the bit depth to be used by n-Track so with the 16 bit version of the program you'll always hear the nagging sound. You can use WDM drivers in 16 bit mode selecting them in the File/Settings/Audio devices dialog box. There is no advantage in using Asio drivers over WDM as both can achieve very low latencies.