Hi there Steven,
Thanks for reaching out and sorry to hear about this issue. Let’s fix it!
It looks like you may not have actually downloaded Events Calendar Pro for your site. This is a separate plugin, and requires the free version of The Events Calendar to remain installed and active on your site. You can get this by going to My Account » Downloads on our site.
Install and active this plugin by uploading the zip file to your WordPress site. Once activated, go to WP-Admin » Events » Settings » Licenses and add the license.
The confusion here is that our additional service of importing events, known as Event Aggregator, displays another field in the free version where you can add a license. Sorry about that!
Please let me know if this solves the issue,
Best,
Nico