By default Dashboards.JS runs in trial mode with a watermark; registering your license key removes it.

In React.
import { Viewer, Stimulsoft } from "stimulsoft-dashboards-js-react/viewer";

function App() {
    // Register your license from JavaScript code
    // Stimulsoft.Base.StiLicense.key = "6vJhGtLLLz2GNviWmUTrhSqnO...";
    // Stimulsoft.Base.StiLicense.loadFromFile("stimulsoft.key");

    var report = new Stimulsoft.Report.StiReport();
    report.loadFile("Dashboards/Dashboard.mrt");

    return <Viewer report={report} />;
}

How it works. The license is registered before any component is created, so every dashboard renders without the trial watermark.