Hi there,
If they are separate unique projects, then you need a license for each. If they are just the same, then just one license.
But, you need API Key for both to enable automatic updates. You can only have 1 API Key per License, so what you need to do is revoke and regenerate API Key for each of your installation. Please note that API Key is not license key, it’s just a way to enable automatic updates and installation.
Thanks.