Ultimate Addons for Elementor is a plugin that extends the elementor page builder and adds more widgets in it.
Once you install the plugin you can register UAE license key to get remote auto updates, support and unlocking other goodies for your website.
You can refer to the article here to know where you can find the License key.
To activate license of Ultimate Addons for Elementor, navigate to WordPress Dashboard > Plugins > Ultimate Addons for Elementor > Activate License.
Enter your license key in the popup box and Activate your license.