Why actually printing is a paid service? Unfortunately technically it is not possible to print from web application/Odoo.sh on your printer without downloading PDF. This is a technical limitation of printing protocol (so problem not with Odoo but with ANY web software). That is why there are many services like printnode and all of them are paid and all more or less of the similar price. So if you are looking for something that will be printed from Odoo directly for free – there is only one solution for this. Hire team of developers. Get VPN service setup between your office where all your printers are located and develop your own functionality based on Community work.
About payment for the module itself. As you can see prices on https://print.ventor.tech/ are the same as on http://printnode.com. We pay http://printnode.com ourselves for a Developer Account a monthly fee. So most of your subscription fee just goes directly to Printnode and we are different companies of course.
Payment for the module allows us to develop it constantly. If you look at our Changelog (on the “Documentation” tab of the module on the App Store) – we release and improve every month by adding new features. Without that payment it will be very hard to have a support team and there will be no team of developers constantly adding new features and releasing modules for new Odoo versions.