I got an e-mail on the November 20th with the coupon link and instructions. The link was valid for 7 days and the instructions are below.
How to Upgrade
1. Login to your AppThemes customer account
https://www.appthemes.com/login/
2. Go to the Pricing page
http://www.appthemes.com/pricing/ and select the “Add To Cart” link under the relevant AppThemes Club Package (standard or developer)
3. Click on the following URL to apply the coupon code to your purchase (coupon link was here)
5. The final stage of the checkout will reveal if the coupon has taken effect. Complete payment