We don't charge anything extra for updates - they're included in the price of the software.
We ship regular updates to add new features, improve performance and fix problems. We apply them automatically for Cloud customers. On-Premise customers will be notified of new updates from the admin interface and can apply them when they choose - updating is a one-click process on most configurations and usually takes minutes.
See the Product section of our News area to see the features we've added recently.