The purchase price in the order can be displayed in edit mode, view mode, or not displayed in the order at all. This can be configured in the "Orders" section.
If you select the option "Do not display", the "Purchase price" column is not displayed.
The "Display in view mode" option is useful for cases when the purchase price of the product depends on the batch from which the products are taken for the order. In this case, the purchase price is static and changes are not possible.
If you choose the "Display in edit mode" option, the purchase price can be changed.