To install the premium version of Books Gallery on your dashboard, you need to first upload the downloaded file. So, go to the Add New option on the Plugins menu of your dashboard.
There, click on the Upload Plugin button and then the Choose File button. Now, upload the downloaded file here and press the Install Now button beside it.
After the installation completes, you can see the Activate link. For the activation, click on it and then, it’ll ask for the license key. So, add your license key and lastly, click on the button Activate.
Once the process completes after a certain time, the plugin gets completely installed and activated on your site.
Don’t forget to configure the settings as in the free version for your premium version as well.