1. Open PrestaShop Admin, go to the System Menu Item.
2. In the Configure Menu, Select Advance Parameters.
3. Click on Advanced Parameter and select Webservice.
4. After Click Webservice, enable Prsetashop's Webservice.
5. Then, Add New Webservice Key on top of the bar.
6. Then Click on Generate key button.
7. After that set Status Yes and also set the Permissions for (categories, customers, employees, images, languages, products, shop_urls, shops, stores).