my-pmproio-number-of-invite-codes-filter.php

<?php
/**
 * This is an example recipe for using the pmproio_number_of_invite_codes filter.
 */

// [Optional] Set default number of codes
// define( 'PMPROIO_CODES', 2 );

global $pmproio_invite_required_levels;
$pmproio_invite_required_levels = array( 14 ); // Level 14 requires invite code

global $pmproio_invite_given_levels;
$pmproio_invite_given_levels = array( 4, 5 ); // Members of these levels are given invite codes

function my_pmproio_number_of_invite_codes( $quantity, $level ) {

	// Set number of invite codes per level
	$invite_codes_per_level = array(
		4 => 2, // Level 4 receives 2 invite codes
		5 => 3, // Level 5 receives 3 invite codes
	);
	foreach ( $invite_codes_per_level as $level_id => $level_codes ) {
		if ( $level === $level_id ) {
			$quantity = $level_codes;
		}
	}

	return $quantity;
}
add_filter( 'pmproio_number_of_invite_codes', 'my_pmproio_number_of_invite_codes', 10, 2 );

https://gist.github.com/ipokkel/97e887272dc718b3b22a69a51dfbf04a