A corrupt authorization file issue can be resolved by following the steps outlined below:
Open License Manager and log in with your FXpansion account details.
Head to Products -> 'De-authorize and remove product(s)'.
Select the product causing the issue and click 'De-authorize' in the bottom-right corner.
Follow the on-screen instructions to complete the de-authorization.
Once this is complete, close and re-open License Manager and you should be able to authorize successfully.