If the plugin ‘hangs’ when you add the licence information or if you see this message
“Oops… BookPress requires an access to our API. From unknown reason, the API connectivity test failed. It’s probably a temporary issue on our end. Just to be sure, with your permission, would it be o.k to run another connectivity test?”
you will see some options to try and resolve the issue.
If the suggested options do not work it is likely that they problem is that your server host is blocking access to our licencing website and so the plugin cannot validate your licence.
You will have to contact your hosting company and ask them to whitelist api.freemius.com (220.127.116.11) & wp.freemius.com (18.104.22.168) port 8080 for external connection