Is this for the Zoiper app licence or for the config? - It is for the both.
Does it not stay "not registered" after a while?
The fact that you're seeing the information populated here means that everything got provisioned, but your phone is not registering with the PBX.
Turn on the admin level logs for "SIP" > " register" to level 9 and see what logs you see when your hit "register" on the zoiper account on the phone.
You will either find the error there or logs will be empty, meaning, the phone was never able to reach the server. which means it's your network issue.