I’ve reset your license key, please go to Event Espresso -> General Settings.
Remove the key from the license key field and save the settings, then re-add the key and save the settings once again, you can copy you license key from your account page.
Secondly, we are unable to get multiple tickets for events to save and show. If we add them in the event setup page, they show initially until the event is published or updated and then they disappear. Meaning we can only have one ticket per event. We have tried disabling all other plugins and switching the WP 17 theme, but this has no effect.
Hmm, that’s odd.
So you’ve tested with both only EE activate on the site and using TwentySeventeen at the same time?
Do you have access to the servers error logs? If so any errors from EE there?