Commercial License Copyright (c) 2020 Material-UI SAS MUI X Pro (https://mui.com/pricing/) is commercial software. You must purchase a license and agree to the End User License Agreement (EULA: https://mui.com/r/x-license-eula) to be able to use the software. Commercial licenses can be obtained at https://mui.com/r/x-get-license?scope=pro. You are free to install and try the software without a license key as long as it is not used for the development of a feature intended for production use. You can find more details under the "Evaluation (trial) licenses" section of the EULA.