In order to use this service, you have to attach your subscription via the Ubuntu Advantage token. On Ubuntu Pro the subscription is already attached and you must skip this step.
To attach subscription, simply visit the UA portal.
You’ll have to log in with your Ubuntu Advantage or Free account if you haven’t done so already.
The portal will return your subscription credentials and instructions to apply them on the system. Follow the instructions and attach the system to your Ubuntu Advantage or Free subscription. It is as simple as
$ sudo ua attach [TOKEN]