Subscribe user to Convertkit tag after EDD purchase

update_ck_with_customer_tag.php

<?php

add_action( 'edd_complete_purchase', 'draw_update_ck_with_customer_tag' );

function draw_update_ck_with_customer_tag( $payment_id ) {

	$ck_customer_tag_id = 1234;
	
	$edd_payment = new EDD_Payment($payment_id);
	
	$email = $edd_payment->email;
	
	drw_update_ck_subscriber( $email, $ck_customer_tag_id, 'subscribe' );

}