Creating A 3Rd Storefront Without A Licence For A 3Rd

So if I create a 3rd storefront without a licence for a 3rd, will the 3rd only be in 'free' mode?

There is no longer a free mode available.

so I've just created a 3rd storefront and it's working in what capacity?

I couldn't tell you. I've never used more than 1 storefront.