Seth Yoder

When you password-protect a post in WordPress, a cookie is set to expire in 10 
days which prevents the user from having to enter the password during that 
10-day period. This plugin allows you to easily change the lifetime of that 
cookie.

Password Protection Expiration

Allows you to easily change the lifetime of the WordPress cookie which allows automatic login to password-protected posts.

Marco Alluvion

The Media Expirator plugin allows users to set expiration dates for media library items. When the date is reached, the file will be automatically delete from the media library.
User can enable/disable expiration date for each media items directly in media editor.
This plugin is translatable.
<h3>Note</h3>
How to: 
Enable/Disable and set an expiration date for each items directly in WordPress media editor.
Goals: 
√ add enable/disable option 
√ plugin translatable 
√ add translations 
• create option page 
• enable time 
• time zone option 
• media types option 
• optimize code 
• ..add other ideas

Media Expirator

It works!

Media Expirator plugin allows users to set expiration dates for media library items.

Password Protection Expiration vs Media Expirator