You can mark the order as "completed" in two different ways:
In the overview of the "Purchase order" module you can checkmark the respective order. Select "mark as completed" from the dropdown menu in the Bulk Batch Processing area and click "Execute".
Open the specified order and go to the tab Details > Protocol and select the action "complete order" from the dropdown menu.
The articles are now booked out of the goods receipt.
The order is then given the status "completed". If you click on it later, you will still see the originally ordered items and a difference to the liability. This is still correct.
You can find more information in our manual: