Subscription
A pricing model where a customer pays an ongoing fee for services.
Most commercial CMS is priced with a one-time fee for the actual license, and annual subscription for extra services – commonly test and staging server licenses, support, and upgrades.
Some subscription fees include the license itself, which means that failure to pay subscription invalidates the license. Other subscription fees exclude the license (which is paid with a one-time, upfront fee) so that customers can cancel subscription, lose the additional services, but continue using the software.