I downloaded the V7.20 from the appropriate location (password protected). and installed the new product. It did not ask for the Auth COde, but I thought that might be normal for an update.
I recompiled and ran my application, but it identified itself as the Personal Edition. Looking at Programs and Features, both 7.10 and 7.20 showed.
I removed the 7.10 and 7.20 versions (uninstalled). There are some registry entries that are still hanging around. I left those alone.
I installed the 7.20 version. It did not ask me for the authorization code. When I compile and run the application, it still identifies as the Personal Edition.
I seem to have run into this before, but don't see any posts here about what to do.