We hear this concern frequently:

"I'm considering buying CCC, but I am concerned that a new OS will come out and I will be asked to purchase a new license to continue using CCC."

Generally when a new OS is released, we offer a free update to CCC that allows users to continue using it with the same license on the new OS. That has been the case with 8 out of the last 9 major OS releases over the last 13 years, with the notable exception being Yosemite, which broke CCC 3. That being a recent experience, many users share this concern. I would like to succinctly alleviate these concerns with the following statements:

CCC 4 will be qualified and supported on OS X 10.12. We will issue a free update for that OS, just as we did for 10.11 El Capitan.

CCC 4 license holders will not be prohibited from using CCC 4.1.5 (or later) on OS X 10.13 and later

In the past, CCC refused to open on newer OSes* because we were concerned that a future OS version would break CCC in a manner that could lead to data loss. CCC 4.1.5 introduces a mechanism that can proactively warn users if this situation arises, so we no longer restrict that version of CCC from running on a future version of OS X. If you're interested in the longer version of this explanation, see this article: Coping with Apple's pace of innovation in an application that can delete files.

* Again, though, understand that CCC 3.5.7 was broken on Yosemite. While the aforementioned restriction would prevent that version of CCC from opening on Yosemite, it was the underlying architectural limitations of CCC 3.x that made it not work on Yosemite.