Microsoft published revised detection logic for App-V 4.5 SP2 so that Microsoft Update/WSUS willn't offer App-V 4.5 SP2 update if you don't have AER installed on App-V client. To install Microsoft AER read here for complete steps.
Note If you need to find product code, you can use Orca.exe database editor or a similar tool to examine Windows Installer files to find value of the ProductCode property. The tool is avilable in Windows SDK Components for Windows Installer Developers.
More Info About: Orca