Development/Staging/Production -> Multiple Licenses?

Just purchased TotalPoll Pro for Wordpress. We’re running a professional setup where I have my local development machine, a staging server and a production server. Do I honestly have to buy 3 licenses in order to properly develop an extension to this plugin? I do not want to test out my code on a live production server, nor can I put test data up on said server. I need to do all of this locally, have the business stakeholders test it on stage, and then put the working code into production. Is there a way I can do this without having to buy 3 licenses?

The way I understand the license regulations, the license applies to the final live website that is open to the public. Matching sites on development and/or staging servers can share the same license, as long as you ensure that only one site can be publicly accessed. At least, that’s how approach licenses for my items on sale on Envato, whenever a client inquires about it.