Yes — the project is Apache 2.0 licensed (
https://github.com/dgtlmoon/changedetection.io/tree/master?t...), which permits forking and commercial use. There's also a COMMERCIAL_LICENCE.md in the repo for hosting/resale cases, and I've reached out to the maintainer directly about it. Attribution is here:
https://docs.sitespy.app/docs/acknowledgements