Consider a scenario with three products. X, A and B:
X belongs to my company and is not open source.
A is also not open source, but they have free version and paid version with different licenses.
B is under CC BY 3.0 US.
A uses B, and thus, it has to attribute B, which they do on their website.
Now X buys the paid version of A, so it gets a commercial redistribution license, which as per our understanding, does not require attribution to A given the product A is unchanged while being used in product X.
Product X is a paid, non a distributive product, but its services are used for others, but still not by others.
The question here is that do production X have to attribute to B, publicly? They clearly don't have to attribute to A publicly.
I asked this question on TNB and some discussion happened there.
For my specific case, product A is MaxMind GeoIP2 (scroll down for attribution to product B) and product B is Geonames and the commercial license of paid version of A, MaxMind GeoIP2, is here. But this question can be useful for anyone facing similar situation.