newscoop / plugin-NewscoopPaywallBundle

        $attribute = $duration['attribute'];

        $timeSpan = null;

        switch ($attribute) {

            case Duration::MONTHS:

                $diffrence = (int) $now->diff($createdAt)->format('%m');

                $months = $value + $diffrence;

                $timeSpan = new \DateInterval('P'.$months.'M');

                break;

            case Duration::DAYS:

                $daysDiffrence = (int) $now->diff($createdAt)->format('%a');

                $days = $value + $daysDiffrence;

                $months = $value + $diffrence;

                $timeSpan = new \DateInterval('P'.$months.'M');

                break;

            case Duration::DAYS:

                $daysDiffrence = (int) $now->diff($createdAt)->format('%a');

                $days = $value + $daysDiffrence;

                $timeSpan = new \DateInterval('P'.$days.'D');

                break;

        }

        return $startDate->add($timeSpan);