The installation procedure is similar to that of any other plugin. So you have three possibilities to add and keep the plugin up to date.
Envato Market WordPress Plugin
Allows you to keep your plugins up to date automatically and easily.
From the WordPress administration
When you want to update the plugin from the administration, make sure you have disabled and uninstalled the old version before proceeding with the new installation.
Make sure to deactivate the plugin before uploading the new version via FTP.