The customer is responsible for making sure the software will work in their environment. To facilitate the evaluation process an unlimited demo of all software products is available along with free phone and email support. If the test cases work with the twenty concurrent users available in the demo, then any errors from the larger number of concurrent users in the real version are the result of the website's inability to handle load, not a software error.
Once the customer has made a purchase, returns of the software are allowed for a period of 90 days, only in the case that the software fails to produce the advertised load on the web server, provided this can be verified by technical support.