foreach ($users as $user) {    
$userid = $user->id;    
$url = 'https://users.de/api/Get.php?users=' . $userid . '&pro=pro&secret=digital1';     
echo $url; 
}

<?php foreach ($users as $user): ?>
    <?php $url = 'https://users.de/api/Get.php?users=' . $user->id . '&pro=pro&secret=digital1'; ?>
    <?= $url ?><br>
<?php endforeach; ?>