Track membership level as Custom Dimension 1 (dimension1) in your Google Analytics tracking code.

my_pmpro_membership_level_gadwp_analytics.php

<?php
/**
 * Track membership level as Custom Dimension 1 (dimension1) in your Google Analytics tracking code.
 *
 * Requires Paid Memberships Pro and the Google Analytics Dashboard for WP by ExactMetrics (formerly GADWP) plugin.
 */

function my_pmpro_membership_level_gadwp_analytics( $gadwp ) {
	$commands = $gadwp->get(); // Get commands array
	
	// Get the value to track for the current user.
	if ( is_user_logged_in() && function_exists( 'pmpro_getMembershipLevelForUser' ) ) {
		// Get the current users's membership level ID. 
		$current_user_membership_level = pmpro_getMembershipLevelForUser( get_current_user_id() );
		$value = $current_user_membership_level->ID;
	} else {
		// Set the tracked membership level ID to no_level.
		$value = 'no_level';
	}
	
	$fields = array();
	$fields['option'] = 'dimension1';
	$fields['value'] = $value;
	if ( $fields['value'] ){
		$command = array( $gadwp->prepare( 'set', $fields ) );
		array_splice( $commands, -1, 0, $command ); //insert the command before send
	}
	$gadwp->set( $commands ); // Store the new commands array
}
add_action( 'gadwp_analytics_commands',  'my_pmpro_membership_level_gadwp_analytics', 10, 1 );

This recipe is no longer supported by the updated GADWP version that was purchased by Exact Metrics. Please use this recipe in its place: https://gist.github.com/kimcoleman/1114506c1c3e6177c495e3664c6013bb