Yes! You can choose which group of subscribers receive specific Email Updates.
When drafting a new Email Update, click on the drop-down menu underneath 'Audience Access Settings' section. The default option is set to 'Free (All Users)' but you can change it each time you're working on a new email.
Select 'Paid Subscribers' from this menu and a second drop-down menu will appear. Select the name of your Premium Subscriber tier in this second menu and you're all set!
When you send the update, only your premium subscribers will receive it in their inbox and access it on the Zestworld website.