woocommerce_process_product_meta_simple usage sample

woocommerce_process_product_meta_simple.php

<?php

add_action( 'woocommerce_process_product_meta_simple', 'save_options' );
function save_options( $product_id ) {
	$keys = array(
		'_ppwp_woo_protected_post',
		'_ppwp_woo_usage_limit',
		'_ppwp_woo_expiration',
		'_ppwp_woo_custom_text',
		'_ppwp_woo_protection_type',
	);

	foreach ( $keys as $key ) {
		if ( isset( $_POST[ $key ] ) ) { // phpcs:ignore
			update_post_meta( $product_id, $key, $_POST[ $key ] ); // phpcs:ignore
		}
	}
}