SoundCloud Go tracks are only available as 30-second previews in embedded players. As it is not possible to sign in to an embedded player, SoundCloud cannot recognize if you have a SoundCloud Go subscription to give you access to the full track.
To listen to the entire track with a SoundCloud Go subscription, simply click the SoundCloud icon on the top right of the embedded player to listen from SoundCloud.com while signed into your account.
Sharing the link to a SoundCloud Go track on Facebook (Web) will create a visual embed containing a 30-second preview of the track. Hitting 'Listen on SoundCloud' will take you to the track on SoundCloud.
Note: from a mobile device, any Facebook embed will appear as a regular redirect card that will take you to the track on the SoundCloud app, if you have it installed, or to the Google Play/Apple App Store.