Ask HN: How do you know which model is hidden behind the API?

We know that Llama weights are not for commercial use, but suppose somebody served Llama(or any other model) via Web interface or API, how do you know which model it is? Does Facebook have magic prompts that returns an ID? What happens when the model is finetuned or a delta is applied to the weights?

Now that there is an explosion of apps building on various LLMs, the copyright of LLMs doesn't seem to be very well defined, will LLMs have DRM in them in the future?