fergbrain

Forces new users to register additional fields. Available fields are:
<ul>
<li>First Name</li>
<li>Last Name</li>
<li>Nickname</li>
<li>AIM screen name</li>
<li>Yahoo IM screen name</li>
<li>Jabber/Google Talk user name</li>
</ul>

Force User Field Registration

Forces new users to register additional fields (such as first name and last name). Note: WordPress 2.5 or higher is definite required due to new erro …

Kowsar Hossain

If you want to make coupon code as a required field, this plugin will help.
During checkout when a customer will try to place an order without entering any coupon code, checkout process will be interrupted and customer will see an error notice.
You can configure the error notice text from “WooCommerce>Force Coupon” menu from admin panel.

Force Coupon for WooCommerce

A lightweight WooCommerce based plugin to force the customer to enter a coupon code during checkout

Force User Field Registration vs Force Coupon for WooCommerce