Hello Erik, the software I wrote and am about to sell was developed for use by German Hospitals only. It's being used to calculate a departments share of the revenues paid by the insurance companies for a case and needed every 6 months by the hospitals when it enters budget negotiations with the insurance companies. It could for instance not be used by Hospitals outside of Germany. I think it is unlikely that the Hospitals would try to "hack" my application but thanks for the concern. But I do need something in place, something that will check if the hospital is using a licensed version. It is also expected on the customers side otherwise the customer would not even consider using the software but reject it outright. Best regards Günther