Hi there,
It seems that you are putting your license key for The Events Calendar Pro into the field for Event Aggregator. This is a completely different product, and only shows there because it is a cloud based service as opposed to a plugin that you install.
You will need to download The Events Calendar Pro from your account, install and activate on your site.
Once activated, the field for your TEC Pro key will show in the Licenses tab just below the one for Event Aggregator.
Hope that helps.
Thanks,
Sky