You only need these terms to make a buying decision
You do not need to master every concept first. It is enough to know what each boundary actually controls.
Credited usage balance
This is the platform-side balance used to account for model usage. It is not a cash refund and not a withdrawable wallet balance. If you only want a rough USD conversion, simply divide the credited amount by 7.
Daily limit
The maximum usage balance you can consume in one day. It is mainly a daily budget boundary and resets on the Beijing-time natural day.
RPD
Requests Per Day. Think of it as how many sends or API calls you can make in one day. One AI agent task may fan out into multiple API requests under the hood, so what feels like one task can consume more than 1 RPD in practice.
TPD
Tokens Per Day. Long contexts and long outputs are more likely to get close to this boundary.
Sub-user access
Lets you assign separate accounts, quotas, and reporting to team members instead of sharing a single key.
Subscription / PAYG / Extra usage
Subscription is for ongoing use, PAYG adds general balance, and extra usage is for subscription users who need more room after a daily cap. As long as extra usage still has balance, the default daily limit no longer blocks you.
Extra note: RPD and TPD are natural-day quotas, not rolling 24-hour windows. If you are only blocked by today's daily boundary, extra usage is usually the right next step. As long as extra usage still has balance, the default daily limit no longer blocks you.
Common questions
These cover the most common points of confusion when someone is buying for the first time.
Why is the plan price not 1:1 with the credited usage balance?
A subscription plan is not a simple 1:1 top-up. The price is the monthly fee, while the credited usage balance is the resource pool available for that billing cycle. It is not cash back and not a withdrawable wallet balance. If you only want a rough USD conversion, simply divide the credited amount by 7. For most users, the more important question is whether the plan matches their daily usage level and whether they need sub-user access.
Which models do Codex plans actually support? Can I use them from Claude Code?
Our main offer is the Codex plan family. The core models are gpt-5.5, gpt-5.4, gpt-5.4-mini, gpt-5.3-codex, and gpt-5.3-codex-spark. This model set works well in Codex CLI / App and direct API usage. It also supports Claude API compatibility, so Claude Code can use the same subscription resources. The default mapping is claude*=gpt-5.4 and claude-haiku*=gpt-5.4-mini.
Why do I still have balance, but I cannot continue today?
The usual reason is not that your total balance is gone, but that you hit a daily boundary such as the daily limit, RPD, or TPD. In simple terms: total balance answers "how much is left", while daily limit, RPD, and TPD answer "how much can I still push today". If your subscription balance is still there but today's boundary is exhausted, extra usage is usually the correct next step. As long as extra usage still has balance, the default daily limit no longer blocks you.
Should I start with a subscription plan or with pay-as-you-go?
If you use Codex, Claude Code, or similar coding clients every day, start with a subscription plan. If you only call APIs occasionally, are still testing, or care more about paying strictly by actual usage, start with pay-as-you-go. A simple rule is: if you do not yet know whether your usage will stay consistently high, start with a lower tier or PAYG and see whether you regularly hit the daily cap within a week.
Can renewals stack? Can I upgrade online by paying only the price difference?
Yes. When you renew the same tier, the usage credits and validity continue to stack. If you later find the current tier too small, you can also upgrade online by paying the price difference. In practice, that means you can start lower, observe your real usage, then renew or upgrade without locking yourself into the first choice forever.
What is the difference between extra usage and pay-as-you-go?
Pay-as-you-go is more like adding general usage balance to the account. Extra usage is designed for subscription users who still have subscription resources but need more room after hitting a daily boundary. As long as extra usage still has balance, the default daily limit no longer blocks you and extra usage continues to absorb the rest of that day's consumption. In short: PAYG is general-purpose balance, while extra usage is the daily-overflow tool for subscribers.
How should I choose between Responses API and Claude API?
Start from your client, not from the model name. Codex, new projects, and tool-calling workflows should usually use Responses API. Claude Code and Anthropic-compatible clients should use Claude API. For most users, the rule is simple: default to Responses, and use Claude API in the Claude ecosystem. These are compatibility layers, not separate pricing systems.
What is the practical value of sub-user access for a team?
It lets you assign separate accounts, quotas, limits, and reporting to each teammate instead of sharing one master key. As soon as multiple people share the same resources, you run into questions like who consumed what, who hit the limit, and how to separate permissions. Plans with sub-user access are built for that team-governance scenario.