Fanatical was originally alerted to this problem on 6th January.
We can assure you this is the full version.
After reporting this issue to the developers, we quickly received feedback that this IS the full version. The integration with Unity has erroneously left a 'trail version' warning for some users in the corner of the screen.
The developers are in the process of updating the product and the trial version message will disappear during the next product update. However, currently there is no date set for the update.
We hope this reassures you that there is nothing wrong with your key and the erroneous message will be removed soon.