EDpuzzle is 100% free for teachers and students. The gradebook and all the premium features are built so that schools pay for them, not the teachers. We decided that we will never charge teachers. Education seems to be the only industry where a worker pays for the tools used at work.
As former teachers, we don't think teachers should be an exception.
So if you think the school might be interested, more than happy to help you with that process. :)