This e-mail from them helped:
if you are missing some features in the software, you may be using the .NET version.
The .NET version is the "play money only" version of our software used in advertising, and does not have features such as instant hand reply. These options are available in the full-feature version of the software, which you can download from our website at:
http://www.pokerstars.com/poker/download/
Since both versions may be installed on your computer, you may want to uninstall the .NET software to avoid any further confusion.