The Nutritower comes standard with 24 pots. We suggest this to start off with as there is a bit of a learning curve with hydroponics.
Once you are comfortable with the system, you can easily start customizing to accommodate another 24 small pots, for a total of 48. This requires a simple expansion kit available late 2016. The 48 pot setup requires a little more maintenance as there is double the plants to look after so the water level will decrease more rapidly, but the yield is also double :)
Also in development is a larger pot that will better accommodate plants such as cucumbers and tomatoes. This add-on will allow you to have a combination of 24 small pots and 12 large, or a variety of configurations in between.