Savan Dholu

This Plugin gives you the functionality when the user clicks on Add to Cart button it will clear all previous cart data entirely and add new cart data, only allow one product purchase at a time.

Allow Only Last Item In Cart

Just added working automatically 
Relevant and Better!!

An Amazing Plugin

This Plugin gives you the functionality when the user clicks on Add to Cart button it will clear all previous cart data entirely and add new cart data …

Silkalns

WP Chill

Cristian Raiber

A very useful plugin for everyone using WordPress. Adds reCaptcha security to the WordPress login form, register form and comment form. This plugin could help your blog get rid of a lot of spam comments or brute-force attacks.
Nothing gets passed it if the reCaptcha doesn’t validate.
A few notes about the plugin:
<ul>
<li>Supports audio or image captcha types</li>
<li>Can generate the reCaptcha image / audio type in a number of predefined languages</li>
<li>Adds reCaptcha protection to the WordPress login form</li>
<li>Adds reCaptcha protection to the WordPress register form</li>
<li>Adds reCaptcha protection to the WordPress comment form</li>
<li>Adds reCaptcha protection to the WordPress recover password form</li>
</ul>

Uber reCaptcha

This plugin adds the reCaptcha form to the WordPress login form, recover password form, register form and comment form.

Allow Only Last Item In Cart vs Uber reCaptcha