Morteza Geransayeh

WooCommerce lets you set a coupon “Expiry date” but not an exact time. 
This lightweight plugin adds a “Coupon expiry time” field (HH:MM, 24h) to the coupon edit screen. 
When both date and time are set, the coupon will expire on that date at the time you specify.
Key points 
* Works alongside WooCommerce’s native coupon expiry date. 
* Time is stored internally as seconds since midnight and combined with the date. 
* No changes to your theme or checkout templates required.
<h3>Usage</h3>
<ul>
<li>Set Expiry date as usual in WooCommerce.</li>
<li>Set Coupon expiry time in <code>HH:MM</code> (24-hour) format, for example <code>17:30</code>.</li>
<li>The coupon will be valid until the combined timestamp; after that, it will be treated as expired.</li>
</ul>

Expiry Time Coupon for WooCommerce

Add a time-of-day component to WooCommerce coupon expiry that works together with the built-in expiry date.

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Expiry Time Coupon for WooCommerce vs Post Expiry Scheduler