The FullPro version upgrade allows you to use the CNS for circuits and analyses as large as you can, there is no limit but the sky! Well, the other limits are your computer and you. But If you have a somewhat modern computer, and if you know what you are doing, then again the limit is just the sky!
In other words:
unlimited number of components
unlimited number of nodes
unlimited number of datapoints in each analysis
unlimited number of lines in each analysis
Also the FullPro version has all the color modes which the other versions have too, and additionally has the night-mode. The night mode is practical, if you are working long hours in front of the screen. It is less tiring for the eye, and the shining wires model works best on a black background. So if you are working on digital circuits, the night mode is optimal for you!