Based on the search results, here are the pricing models for the LLM inference services of OpenAI, Anthropic, and Google:

### OpenAI
- **Pricing Model**: OpenAI offers a pay-as-you-go pricing model for its API usage.
- **Cost**: As of the latest information available, the pricing for the GPT-3.5 model is $0.002 per 1,000 tokens, while the GPT-4 model starts at $0.03 per 1,000 prompt tokens and $0.06 per 1,000 completion tokens.
- **URL**: For more details, visit [OpenAI Pricing](https://openai.com/pricing).

### Anthropic
- **Pricing Model**: Anthropic provides a subscription-based pricing model for its Claude AI models.
- **Cost**: The pricing for Claude 1 and Claude 2 is set at $0.01 per 1,000 tokens. Specific pricing for Claude 3 has not been disclosed yet.
- **URL**: More information can be found at [Anthropic Pricing](https://www.anthropic.com/pricing).

### Google
- **Pricing Model**: Google Cloud offers its LLM services through the Vertex AI platform, which includes a pay-as-you-go pricing structure.
- **Cost**: The pricing for Google’s PaLM 2 model starts at $0.045 per 1,000 tokens for the standard model and $0.075 for the advanced model.
- **URL**: Detailed pricing can be accessed at [Google Cloud Pricing](https://cloud.google.com/vertex-ai/pricing).

### Summary
In summary, OpenAI, Anthropic, and Google provide various pricing models for their LLM inference services, with OpenAI and Google adopting a pay-as-you-go structure, while Anthropic utilizes a subscription model. The costs vary significantly, with OpenAI's GPT-4 being the most expensive at $0.06 per 1,000 tokens, while Anthropic's Claude models are priced at $0.01 per 1,000 tokens.