Thanks a lot! It is perfect for me!DEMO: https://mypresta.eu/modules/ordering-process/maximum-product-quantity.html
This great PrestaShop addon is one from the most wanted features in PrestaShop. With this module you can specify value of maximum product quantity that customer will be able to order. As you can read in short description - as a shop owner you can define different values of maximum quantity for each product and for each customer group that you have in your online store. Of course if you don't want to create such restrictions - module also allows to do that.