When using a Hot Restart Feature (using Windows only, deploying to iPhone plugged into the Windows PC, via "Local Device") the watermark is presented on the iPhone device even I have a valid license and the build log shows the active license is detected.
In general the Hot Restart is not supported as there are limitations for static libraries. Check this link:
https://feedback.telerik.com/maui/1582732-support-for-hot-restart-feature