whmcsTools/check_billing_cycle.php

<?php

/**
* push current product billing cycle to upgrade form 
* @author Thurdata
*/

use Illuminate\Database\Capsule\Manager as Capsule;

function current_billingcycle_hook($vars)
{
   if ($vars['templatefile']=='upgrade'){

       $id = $vars['id'];
       $billingcycle = Capsule::table('tblhosting')
               ->where('id',$id)
               ->value('billingcycle');
       return array("curbillingcycle" => $billingcycle);
   }
}
add_hook("ClientAreaPageUpgrade", 1, "current_billingcycle_hook");