FlexPDE is authorized by a separate code from SVOffice 2009. The authorization code is not checked until FlexPDE is run at least once. You may see FlexPDE listed as a Student license in the SVOffice 2009 Authorization dialog even if you have a full license, the first time you open your installed software.
To force a FlexPDE authorization check, click on the "Details..." button from the Authorization window to launch the FlexPDE application. The next time the Authorization dialog is opened, the FlexPDE information should be up-to-date.
If you require a trial license for FlexPDE for any reason, follow these steps here.