Set up a maximum order quantity for a product

1. In the Administration panel, go to Products → Products.
2. Click on the name of the product you’d like to edit.
3. Enter the desired number in the Maximum order quantity input field under the Pricing/Inventory section.
4. Click the Save button.

After that, a customer will not be able to order more items of this product, than the number set up in the Maximum order quantity option, at once.