iScreensaver 5.2 has been released, and provides support for macOS High Sierra 10.13. Please read the 10.13 High Sierra Tech Note
as well as the Release Notes
. macOS 10.14 Mojave is under investigation, and is not yet recommended.
[Solved] "created with iScreensaver" overlay
Does the "created with iScreensaver overlay" disappear with a registered version?