OpenAccessGPT is a free, open-source project, but using it - both locally or online - requires access to OpenAI's APIs, which have associated costs. These costs depend on the number of words sent and received from the OpenAI GPT model via API. Detailed pricing information can be found on OpenAI's website: https://openai.com/pricing
To use OpenAccessGPT, you need to provide your OpenAI API key within the chat interface. If you don't have an API key yet, you can generate one by visiting this link and using your OpenAI account: https://platform.openai.com/account/api-keys. If you still don't have an OpenAI account you will have to create one, simply follow the steps clicking on "Sign-up" on their website.
Remember, OpenAccessGPT doesn't handle billing or store credit card information. All payments are managed directly by OpenAI. If you encounter any issues or need to recharge your credit, visit your OpenAI account. API usage is billed separately from ChatGPT plus subscription, this means that even if you are a ChatGPT plus subscriber you will have to re-enter your credit card and you will be billed in parallel for both ChatGPT plus and for on demand usage of OpenAI APIs.
OpenAccessGPT supports also GPT-4. In order to access GPT-4, you can request API access here: https://openai.com/waitlist/gpt-4-api. Keep in mind that there may be a waiting list. Finally, to monitor your usage and costs, visit the OpenAI platform portal at this link: https://platform.openai.com/account/usage