ASEBA-PC is a single user license; you can only install it on one computer.
if you'd like to use it on more than one machine, you have a few options.
1. Purchase multiple licenses for ASEBA PC.
2. Purchase a yearly subscription to ASEBA Web.
ASEBA Web works on a system of e-units. Each form you send out costs two e-units, and you can see the price of additional e-units here:
http://store.aseba.org/ASEBA-Web-Products/products/24/
The primary advantage of ASEBA Web, besides being able to use it on any computer is that it provides informants access to a site where they can fill out the forms themselves. This may save you time since you won't have to key-enter the forms one by one.
3. Purchase ASEBA Network.
ASEBA Network runs on a server on your network. You can then access it from any computer with a web browser. You can see the installation requirements here: http://aseba-network.aseba.org/