Forced upgrade help needed

Recently I was forced to upgrade my Window 8 pro computers to 8.1. After the upgrade I no longer have the pro version with the new 8.1 OS . What is the remedy to this issue. I purchased the pro options for Win 8 but find no path to Win 8.1 Pro other than another purchase. Your advice and support is greatly appreciated.

usually it is control panel > add features > already have key > enter pro key..