brechtryckaert

Limiting the cookie expire time of password protected posts. By default the cookie set when entering a password to access a password-protected post will be active for 10 days. This plugin turns this cookie into a session-based cookie. This means your visitor will need to re-enter the password if the browser was closed prior to revisiting the post.

Instant Cookie Expire

This plugin turns the cookie for a password-protected post into a session-based cookie.

Marcello Scacchetti

Display on password protected pages/posts a custom specified text instead of the WordPress default one.
A few notes about the plugin: 
* Actually doesn’t support i18n, should be supported in the next release 
* Actually doesn’t support message multilingual message translation

Custom Password Protected Text

Custom text message for password protected pages and posts

Instant Cookie Expire vs Custom Password Protected Text