"The beta version of Duple is now available. You can download it and use it for free. However if you’d like to participate in the Duple beta program, and get a lifetime discount as a reward, click here."
But I don't understand what we are paying for going forward. Presumably you pay for the software once. Is there a recurring charge of some sort? What for? If the software is on premise, you can't really turn it off or stop it from working.
Does duple, the company, ever touch the data?
If privacy is the killer feature, it seems that an open source version will ultimately displace this.