From the website of TamoSoft, the manufacturer of TamoGraph Site Survey:
At TamoSoft, we want you to be happy with your purchase. That is why we encourage you to try out our products and technical support free of charge for 30 days before you make a decision regarding the purchase. By making the most of these free evaluations, you can fully test the software and make sure that it does everything you need. If you have questions while you evaluate the software, please don't hesitate to contact our support staff.
Because of this free evaluation practice, we do not refund or exchange software purchases. Once we have created a key file for you and emailed it to the address specified during your order, the software is considered delivered and opened, therefore making it non-returnable. If you have any questions prior to your purchase, please contact TamoSoft Support.