Add new role on level change

add_new_role.php

<?php

function action_pmpro_after_change_membership_level( $level_id, $user_id, $cancel_level )
{ 
	$user = get_userdata($user_id);
	
	if($level_id == 1)
	{
		$user->add_role( 'editor' );
	}
	if($level_id == 2)
	{
		$user->add_role( 'author' );
	} 
}
         
// add the action 
add_action( 'pmpro_after_change_membership_level', 'action_pmpro_after_change_membership_level', 1, 3 );