How much does chat gpt-4 cost?

I'm curious, what is the pricing structure for using Chat GPT-4? Is it a one-time fee, a subscription model, or perhaps a pay-per-use system? Are there any discounts available for frequent users or those who commit to longer-term plans? Additionally, are there any hidden costs or fees that users should be aware of before signing up for the service? I'm eager to learn more about the financial aspects of utilizing this advanced AI tool.