If the key doesn't have limitations in terms of OS compatibility and online activation, then you can use the CD if you have one and install it on Windows 7. Make sure to apply a compatibility tweak before doing this. Right-click the setup package and choose Properties > Compatibility. Select Windows XP on the list then launch it as Administrator and follow the installation guidelines.
After the software has been installed properly, start it and put in the code. If it doesn't work, then the developers will provide additional help: http://www.coursedesigner.com/contact