All CKFinder licenses are lifetime and perpetual. Your right to use and distribute the purchased software never expires.
Each purchase also gives you the right to upgrade CKFinder to all newer versions released within a year after you buy a license as well as to use the dedicated support channel during this time. After a year from the date of your purchase your access to the support channel is terminated and you can no longer upgrade CKFinder to versions released after this time.
Each license can be renewed yearly at a discounted price in order to make it possible for you to take advantage of latest CKFinder versions and maintain access to professional assistance from our development team. To renew your license, just go the the official CKFinder website and scroll to the License Renewal section.
The full text of the CKFinder License Agreement is available here.