The price is for a single PC license price.
Multiple PC installations require multiple licenses.
If you need to install Netkiosk on just 1 or 2 PCs a few single licenses might be ideal for you. If you want to install Netkiosk on a lot of PCs check out Netkiosk Freedom.
With Netkiosk 2018 you get all current Netkiosk versions.
Simply use the version that best suits your needs.