The product license is applied from code before any report is used. This example shows where to set the license key or load it from a file.

License setup. Load or assign the license at application startup, before the first report component is created.
import { Viewer, Stimulsoft } from 'stimulsoft-reports-js-react/viewer';

function App() {
    // Using one of the functions below to register your license from the JavaScript code

    // Stimulsoft.Base.StiLicense.key = '6vJhGtLLLz2GNviWmUTrhSqnO...';
    // Stimulsoft.Base.StiLicense.loadFromFile('stimulsoft.key')

    var report = new Stimulsoft.Report.StiReport();
    report.loadFile('Reports/SimpleList.mrt');

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

export default App;

Assigning StiLicense.key or calling StiLicense.loadFromFile at startup removes the trial banner; the key can be embedded as a string or kept in a separate stimulsoft.key file.