The Pro version of Premium Add-ons is an extension for the free, so you need to have Premium Add-ons for Elementor installed and active on your site, in order to find the license tab and enable all the Pro features.
Improve User Interaction and Site Speed with Elementor AJAX Search Widget and Premium Addons Updates
The recent update of Premium Addons for Elementor has brought notable enhancements to both its Free version 4.10.29 and PRO version 2.9.15.