Unless I'm mistaken, it can be used for commercial uses as well, but only under the `Creative Commons Attribution-ShareAlike 4.0 International License`, which, for an API, might imply everyone using the API to also use the data obtained in accordance with that same license, but IANAL.
By third party, do you mean this github repo? This app is also just using the maxmind data, afaict and providing the info in that db over the web.
By third party I mean the API. You can easily embed the database using a library in every programming language I’ve ever seen. There is no reason for another API, and there is no reason for another risk factor by trusting that this new API is correct.