mortenf

This plugin adds optional per-page user name and password protection, implemented using standard HTTP protocol authorization headers, thus triggering the standard user/password dialog of the browser, and making it possible to make the browser store the credentials.
Subpages of a protected page are protected with the same user name and password as their parent.
Protected pages and their subpages do not show up in menus, search results and page lists.
<h4>Usage</h4>
<ol>
<li>When editing a page, locate the section titled “Page Protection” (probably located near the bottom of the right sidebar).</li>
<li>Check the box “Protect page and subpages”, and provide a user name and password combination.</li>
<li>Optionally, check the box “Make page and subpages searchable”, if you want the page and its subpages turn up in search results, but only with their title, not their content.</li>
<li>Save your page.</li>
</ol>
<h3>License</h3>
Copyright (c) 2009 Morten Høybye Frederiksen <a href="mailto:morten@wasab.dk" rel="nofollow ugc">morten@wasab.dk</a>
Permission to use, copy, modify, and distribute this software for any 
purpose with or without fee is hereby granted, provided that the above 
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES 
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Page Protection

Protect pages and their subpages with user name/password, and keep protected pages from showing up in menus, search results and page lists.

wp.insider

smp7

This addon allows you to customize the content protection message that gets output from the membership plugin.
You will be able to specify your custom messages for different types of protection message.
This addon requires the <a href="https://wordpress.org/plugins/simple-membership/" rel="ugc">Simple Membership Plugin</a>.
After you install this addon, go to the “Custom Message” menu from the admin dashboard to use it.
Read <a href="https://simple-membership-plugin.com/simple-membership-custom-messages-addon/" rel="nofollow ugc">Usage Documentation</a>

Simple Membership Custom Messages

Simple Membership Addon to customize various content protection messages.

Page Protection vs Simple Membership Custom Messages