Add a "Forever" option to Limit Orders for WooCommerce - https://wordpress.org/support/topic/all-time-interval/

limit-orders-forever.php

<?php
/**
 * Plugin Name: Limit Orders for WooCommerce - Never-ending Interval
 * Description: Add a "Forever" option to Limit Orders for WooCommerce.
 * Author:      Nexcess
 * Author URI:  https://nexcess.net
 */

/**
 * Add "Forever" to the list of intervals.
 *
 * @param array $intervals Available time intervals.
 *
 * @return array The filtered array of intervals.
 */
add_filter( 'limit_orders_interval_select', function ( $intervals ) {
	// Return early if it already exists.
	if ( isset( $intervals['forever'] ) ) {
		return $intervals;
	}

	$intervals['forever'] = __( 'Forever (never resets)', 'limit-orders' );

	return $intervals;
} );

/**
 * Get a DateTime object representing some time in the past.
 *
 * @param \DateTime $start    The DateTime representing the start of the current interval.
 * @param string    $interval The type of interval being calculated.
 *
 * @return \DateTime A DateTime object some time in the past or $start, if the current $interval is
 *                   not "forever".
 */
add_filter( 'limit_orders_interval_start', function ( $start, $interval ) {
	if ( 'forever' !== $interval ) {
		return $start;
	}

	// Start at the top of the previous hour.
	return $start->setTime( (int) $start->format( 'G' ) - 1, 0, 0 );
}, 10, 2 );

/**
 * Filter the DateTime at which the next interval should begin.
 *
 * @param \DateTime $start    A DateTime representing the start time for the next interval.
 * @param \DateTime $current  A DateTime representing the beginning of the current interval.
 * @param string    $interval The specified interval.
 *
 * @return \DateTime The DateTime at which the next interval should begin, or $start if the
 *                   current $interval is not "forever".
 */
add_filter( 'limit_orders_next_interval', function ( $start, $current, $interval ) {
	if ( 'forever' !== $interval ) {
		return $start;
	}

	return $current->add( new \DateInterval( 'P100Y' ) );
}, 10, 3 );

"Forever" is relative; if your store is online for 100 years, well, here's to your health! 🍻