You can use CloudLinux Selector to enable ionCube Loader in Plesk.
1. Log into your Plesk account.
2. In the right-hand sidebar, Click on PHP Selector.
3. Click on the Extensions menu.
Note: If the Extensions page shows an error related to the native PHP version, change it to a non-native version first.
4. Tick mark the ioncube_loader Once enabled, it will display a success message.
The message will read that the module ionCube Loader is saved.