You must have a web hosting with PHP5 and MySQL5 as well as Flash Player on your computer. Please use the compatibility script to check if PicsEngine can be installed.
It's a one-domain license. With this license, you can install PicsEngine as much as you want, as long as it’s on the same domain name (sub-domains are the same domain).
Minor updates 3.x.x are free.
(read extended conditions)