“Restrict Registration” is a plugin for WordPress that allows you to control 
who is registering on your blog. This plugin uses simple blacklists and 
whitelists to define who can register for your blog, and who is restricted. Use 
simple literal matching, flexible asterisk wildcard matching, or powerful 
regular expression matching: it’s your choice! The options page is clear and 
easy to use. Set your lists, and you’re done!
This plugin was inspired by WP-Deadbolt, but has been completely rewritten and 
redesigned, and several new features have been added.

Restrict Registration

Use simple blacklists and whitelists to control who can and cannot register on your blog.

sunnyverma1984

Increase user registration on blog by making post or page available only for registered user. 
This plugin allows to make post, page or partial content visible to registered users only. You can hide partial content using shortcode <code>[RegUserOnly][/RegUserOnly]</code>. Or you can hide complete post or page by selecting Visibility to <code>Registered Users</code> in post/page editor.
<h4>Plugin Features</h4>
<ul>
<li>Easy installation and integration</li>
<li>Custom tinymce shortcode button</li>
<li>Cross Browser capability</li>
<li>Translation ready</li>
</ul>

Only for Registered Users

Make post, page or partial content visible to registered users only

Restrict Registration vs Only for Registered Users