Hi Karen!
Thanks for your interest in our plugins.
You might want to check out our Community Events plugin, which allows users to submit their own events to your calendar.
With Community Events you can manage event submissions. Users memberships is not something already built-in to our plugins, so you might need to create some custom implementation of a third party plugin to manage subscriptions.
If you want to make a members-only calendar, we have a good article you can use as a starting point > https://theeventscalendar.com/knowledgebase/making-members-calendar/
I know many users integrate our plugins with the WooCommerce Memberships plugins > https://woocommerce.com/products/woocommerce-memberships/
I hope that helps. Let me know if any follow up questions.
Best,
Victor