Our extensions for Magento can be installed in every shop. It does not make any difference whether you start a new shop from scratch or if you have already a shop running.
We have this extension for a few months now. After we did something the extension wasn't working anymore. After contacting Sven, we had very fast response. He looked at the problem by making a account etc. Suddenly the extension worked again, without any problems. Maybe some cache problem. However we were surprised by the fast response and ready to help