public function creditsUsed($model, $key = 'user_id', $value = null)
    {
        if (is_null($value)) {
            $value = $this->user->id;
        }

        $credits = $this->config['plans'][$this->subscription->stripe_plan]['credits'];

        $appModel = app($model);

        $creditQuery = $appModel->where($key, $value);

        if ($this->inBillingCycle) {
            $customer = Customer::retrieve($this->user->meta->stripe_id);
            $stripeSubscription = $customer->subscriptions->retrieve($this->subscription->stripe_id);

            $currentPeriodStart = Carbon::createFromTimestamp($stripeSubscription->current_period_start)->format('Y-m-d h:i:s');
            $currentPeriodEnd = Carbon::createFromTimestamp($stripeSubscription->current_period_end)->format('Y-m-d h:i:s');

            $creditQuery
                ->where('created_at', '>=', $currentPeriodStart)
                ->where('created_at', '<=', $currentPeriodEnd);
        }

        $creditCollection = $creditQuery->get();

        foreach ($creditCollection as $item) {
            $creditCount =+ $item->{$credits['column']};
        }

        return $creditCount;
    }