Don't allow early renewals for certain levels with Paid Memberships Pro.

$pmpro_non_renewal_levels.php

/*
	Don't allow early renewals for certain levels.
	
	Change the level IDs in the $pmpro_non_renewal_levels global array, then
	add this code to your active theme's functions.php or a custom plugins.
*/
//define levels in global
global $pmpro_non_renewal_levels;
$pmpro_non_renewal_levels = array(1,2,3);	//change this to the level IDs of the levels you don't want users to renew for

//hide the renew link
function hide_renewal_links_for_some_levels($r, $level) {
	global $pmpro_non_renewal_levels;
	
	if(in_array($level->id, $pmpro_non_renewal_levels))
		$r = false;

	return $r;
}
add_action('pmpro_is_level_expiring_soon', 'hide_renewal_links_for_some_levels', 10, 2);

//redirect from checkout page to the membership account page
function redirect_non_renewing_levels() {
	global $pmpro_non_renewal_levels;

	//make sure pmpro is active
	if(!function_exists('pmpro_hasMembershipLevel'))
		return;

	//if we're checking out, redirect to account page
	if(!is_admin() && !empty($_REQUEST['level']) && in_array($_REQUEST['level'], $pmpro_non_renewal_levels) && pmpro_hasMembershipLevel(intval($_REQUEST['level']))) {
		wp_redirect(add_query_arg('norenewal', '1', pmpro_url('account')));
		exit;
	}
}
add_action('template_redirect', 'redirect_non_renewing_levels');

//show message on the account page
function the_content_add_non_renewal_message($content) {
	global $pmpro_pages;
	if(!empty($pmpro_pages) && is_page($pmpro_pages['account']) && !empty($_REQUEST['norenewal']))
		$content = "<p><strong>You must wait until your membership expires before renewing.</strong></p>" . $content;

	return $content;
}
add_filter('the_content', 'the_content_add_non_renewal_message');