Order Plesk Add-Ons and Order Plesk Upgrades icons are not available on License Management page.
Show links for purchasing Plesk and add-on licenses option is disabled on a product configuration in Partner Central.
Modify product configuration settings for customer's account in Partner Central:
- open the license in Partner Central
- click on customer's account
- go to Product Configurations tab
- open required configuration (most probably Default Plesk Configuration )
- edit Additional Services menu
- check Show links for purchasing Plesk and add-on licenses box
- no need to specify URL for purchasing licenses
- click Save