I purchased a new license on Aoril 18th and re-installed my theme files (downloaded the latest version of preferential and preferential-child) in order for the new automatic license update function to work as explained in your blog post. The theme update menu now shows in the Appearance menu but it says the license key is invalid when I tried to validate it.
Thanks for letting me know.
I have regenerated all license keys on your account. Could you please login and grab the one for Preferential and re-enter it to the license keys fields, save changes and activate.