Limit order of a product to 1

<div class="hikashop_product_stock">
<?php
	echo $this->cart->displayButton(JText::_('ADD_TO_CART'),'ok',$this->params,$url,$this->ajax,'',$this->row->product_max_per_order,$this->row->product_min_per_order);

<div class="hikashop_product_stock">
<?php
if($this->element->main->product_max_per_order == '1'){
	echo $this->cart->displayButton(JText::_('ADD_TO_CART'),'ok',$this->params,$url,$this->ajax,'',$this->row->product_max_per_order,$this->row->product_min_per_order);
}else{
	echo $this->cart->displayButton(JText::_('ADD_TO_CART'),'add',$this->params,$url,$this->ajax,'',$this->row->product_max_per_order,$this->row->product_min_per_order);
}