An example of rendering a nav bar with links for only the products the current user is active on.

user_active_for_product_nav.php

<ul class="nav">
<?php

$product_ids = array( 'Bronze' => 1812,
                      'Silver' => 8171,
                      'Gold' => 4191 );

foreach( $product_ids as $label => $id ) {
  if(current_user_can("memberpress_product_authorized_{$id}")) {
    $product = new MeprProduct($id);

    ?>
    <li class="nav-item"><a href="<?php echo $product->access_url; ?>"><?php echo $label; ?></a></li>
    <?php
  }
}
?>
</ul>