Hi there, i encountered a bug with the current store framework. I dont know if its the store or the store user upgrade plugin, but i was able to subscribe to user upgrade products in the store with 0 coins. Gifting the upgrade worked as expected (not enough founds error). So i checked the source files and found: brivium/store/controller/public/product.php line 33: $remained = $productPurchaseModel->checkUserMoney($userId, $product, $visitor); if($remained < 0) { return $this->responseError(new XenForo_Phrase('BRS_not_enough_money_to_purchase', array('money' => Brivium_Store_EventListeners_Helpers::helperStoreCostFormat($product['cost_amount'], $product['product_id'], $product['money_type'], $product['currency_id'], $product)))); } EDIT: (stolen from actionGift() on line 85): if(!$remained = $productPurchaseModel->checkUserMoney($userId, $product, $visitor)) { return $this->responseError(new XenForo_Phrase('BRS_not_enough_money_to_purchase', array('money' => Brivium_Store_EventListeners_Helpers::helperStoreCostFormat($product['cost_amount'], $product['product_id'], $product['money_type'], $product['currency_id'], $product)))); } Now it works like a charme #bugbounty ? best regards!