WooCommerce Custom user Meta

/**
 * To display additional field at My Account page
 * Once member login: edit account
 */
add_action( 'woocommerce_edit_account_form', 'my_woocommerce_edit_account_form' );

function my_woocommerce_edit_account_form() {

    $user_id = get_current_user_id();
    $user = get_userdata( $user_id );

    if ( !$user )
        return;

    $cod_fisc_iva = get_user_meta( $user_id, 'cod_fisc_iva', true );

?>
    <fieldset>
        <legend>Dati fiscali</legend>

        <p class="form-row form-row-thirds">
            <label for="cod_fisc_iva">Codice Fiscale/P.IVA<span class="required">*</span></label>
            <input type="text" name="cod_fisc_iva" value="<?php echo esc_attr( $cod_fisc_iva ); ?>" class="input-text" required="required" />
            <br />
        </p>
    </fieldset>

<?php

} // end func

/**
 * This is to save user input into database
 * hook: woocommerce_save_account_details
 */
add_action( 'woocommerce_save_account_details', 'my_woocommerce_save_account_details' );
function my_woocommerce_save_account_details( $user_id ) {
    $input = filter_input( INPUT_POST, 'cod_fisc_iva', FILTER_SANITIZE_STRING );
    $input = wp_strip_all_tags( $input );
    $input = preg_replace( '/[^a-z0-9]/', '', $input );

    if ( ! $input ) {
         return false;
    }

    update_user_meta( $user_id, 'cod_fisc_iva', $input );
}