Think of it in terms of how much money/time it will help you make/save in the long run. Consider it a business expense. Yes, there are other free query builders out there, but they all take time to learn/get used to. If your happy with this one I'd say go for it.
That aside there generally are several ways you can reinstall the program and get one more month out of your free-trial if your still not quite sure its worth it.
