Heads up! Do you just want to restrict content access without requiring payment?
If you want to allow only registered users to access certain areas of your site, we suggest that you take look at this article instead: How do you Allow Only Registered Users to View User Profiles?
While building your site, you might want to require a paid membership to give access to some premium features on your site.
If you want to create membership plans with recurring payments while restricting access to features on your site, we highly recommend the use of the WooCommerce plugin with the WooCommerce Memberships and WooCommerce Subscriptions extensions. These are fully supported by your theme and are hosted by WooCommerce.com with great documentation and support.
If you need directions on how to setup these plugins, we suggest that you take a look at the WooCommerce Memberships Subscriptions Integration article which explains in details how to tie the two extensions together as well as the WooCommerce Memberships Documentation and the WooCommerce Subscriptions Documentation.