A license is sold as a life-time license. You only pay once and use it as long as you want. and on any computer, and you can switch computers, but you may not use a single license at two computers a time. you'll need a license for each computer. However if you purchase a volume license, you can use that on more than one computer. The number of computers in this case may not excceed the number of licenses included in the volume license.

A license will include free technical support, and free upgrade of minor releases and bug fixes. The license does not include major upgrades and new versions of the product. However we may choose to upgrade everyone for free.
Our product works over the Microsoft Windows Network protocole, and if you can setup your needs such that you only install one copy of the software to perform your operations over your network, then only one license is needed.