With WooCommerce Booster Custom PHP module you can add any PHP code that will be executed on your site.
Please note that if you enable the module and enter non-valid PHP code here, your site will become unavailable. To fix this you will have to add `wcj_disable_custom_php` attribute to the URL (you must be logged as shop manager or admin (for this reason custom PHP code is not executed on wp-login.php page)). E.g.: /wp-admin/admin.php?page=wc-settings&tab=jetpack&wcj-cat=emails_and_misc§ion=custom_php&wcj_disable_custom_php
PHP code must be set without the `<?php` tag. After you save module’s settings, new PHP file will be automatically created (and executed) in your uploads folder (in /wp-content/uploads/woocommerce_uploads/wcj_uploads/custom_php/booster.php).