The mail "order confirmation" sent by Eventide contains the Sereial number, but no licence key.

If you buy a plugin directly from Eventide during the purchasing process we deposit the license for the plugin to your iLok account.  We don't send you an email with a serial number and license key b/c there's nothing you need to do to activate your purchase.  You just need to download the installers for the plugin if you haven't done so already, and use the iLok License Manager app to activate your license.

This help page has additional information about the process: 

https://www.eventideaudio.com/support/downloads/installing-and-authorizing-plug-ins