Nix Hi Nix, it's good to hear from you! Yes, that would definitely be fine to show RPG in a Box at a convention. Any word of mouth to help more people discover it is very much appreciated! As long as it's a temporary setup (like for a few days at a convention), that's okay to do, however for permanent setups (like at a cyber cafe, classroom, or other public space where it's always available) a commercial license from Steam for each seat would be needed:
Your scenario is fine, of course, since it would just be a temporary installation at a convention. Thank you for asking! It's exciting to know that RPG in a Box will be shown there. 🙂