OpenRouter tells you if they submit with your user ID or anonymously if you hover over one of the icons on the provider, eg OpenAI has "OpenRouter submits API requests to this provider with an anonymous user ID.", Azure OpenAI on the other hand has "OpenRouter submits API requests to this provider anonymously.".

But does "anonymous user ID" mean that they make a user ID for you, and it's sticky? If I make a request today and another tomorrow, the same anonymous user ID is sent each time? Or do they keep changing it?