Tests to check if you are on certain PMPro pages.

pmpro_is_page.php

<?php
global $pmpro_pages, $pmpro_level;

if(is_page($pmpro_pages['levels'])) {
	//on the pricing/levels page
}

if(is_page($pmpro_pages['checkout'])) {
	//on the checkout page
}

if(is_page($pmpro_pages['checkout']) && $pmpro_level->id == $level_id) {
	//on a specific levels' checkout page
}

/*
  When a checkout is processed, the pmpro_after_checkout hook is fired.
  The only parameter is $user_id.
  You can get the $level_id through global $pmpro_level->id or $_REQUEST['level']
*/

if(is_page($pmpro_pages['confirmation'])) {
	//on the confirmation page
}

if(is_page($pmpro_pages['confirmation']) && !empty($_REQUEST['level']) && $_REQUEST['level'] == $level_id) {
	//on the confirmation page for a specific level
}