Auto-apply coupon to cart at least $25

auto_apply_coupon.php

<?php

// apply free shipping coupon automatically when the cart total is >=$25
add_action('woocommerce_before_cart_table', 'freeship_when_total_at_least_25');
function freeship_when_total_at_least_25() {
    global $woocommerce;
    $cart_total = WC()->cart->get_cart_contents_total();
    if( $cart_total >= 25 ) {
        $coupon_code = 'freeshipping'; // this requires the coupon of this name to already exist
        if (!$woocommerce->cart->add_discount( sanitize_text_field( $coupon_code ))) {
            $woocommerce->show_messages();
        }
        echo '<div class="woocommerce_message"><strong>Discount has been applied: Free shipping on all initial orders over $25!</strong></div>';
    }
}

Context on how to use this: http://nickgreen.info/auto-add-free-shipping-coupon-for-initial-orders-only-for-woocommerce-subscriptions/