The JSpell software is licensed on a per-server and per-domain basis (multi-domain licenses are available for very reasonable costs). Each server, including development, test and production must be licensed. If you have three or more servers it is usually more economical to obtain a Site License. A site license has no restriction on the number of servers that may run the software at your site for the purchasing domain. A site is defined as a single city.
Note, all site licenses allow only one primary technical support contact which is assigned at the time of purchase. If your organization has previously purchased a Site License you may still need another license to obtain direct technical support.