Accessing their API requires an API key, which you can get by creating an account and heading [here](https://platform.openai.com/account/api-keys). Once we have a key we'll want to set it as an environment variable by running:

```bash
export OPENAI_API_KEY="..."
```

If you'd prefer not to set an environment variable you can pass the key in directly via the `openAIApiKey` parameter when initializing the OpenAI LLM class:

```typescript
import { OpenAI } from "langchain/llms/openai";

const llm = new OpenAI({
  openAIApiKey: "YOUR_KEY_HERE",
});
```