One-sentence conclusion: In the billing methods of most AI services, if repeated content is "remembered", reading it again will be much cheaper than the first time. But whether you remember it or not depends not on how important it is, but on where you put it.
This is the most counter-intuitive and practical aspect of "how to spend money on AI".
Phenomenon
The same question is asked twice, but the fees are different. What’s more expensive the first time is cheaper the second time – and sometimes the difference is significant.
The reason is not "AI learned", but two things:
- That paragraphRemembered, so there is no need to read from the beginning the second time;
- or itNot remembered, so you paid the original price again.
Teardown: What will be remembered and what will not be remembered
To put it roughly, the content in a request is divided into two paragraphs:
| Section | Features | Will it be remembered? |
|---|---|---|
| The previous paragraph | Stable, the same every time (fixed instructions, fixed rules, fixed information) | Yes. It’s much cheaper to read after you’ve been remembered |
| The following paragraph | It’s different every time (user’s questions, current data, intermediate results generated in this round) | No. It's new every time, and you have to pay the original price every time |
So the real cost difference is not in "what functions are used", but inWhat content did you put into the stable section?。
On the contrary, if you put things that change every time at the front - such as timestamp, user name, session number - all the parts that can be remembered later will become invalid. This is something that the next article will be dedicated to.
Conclusion
This is aThere is almost no need to change the product, only the order needs to be adjustedAction:
- Concentrate stable content to the front and try not to move it;
- Put the content that changes every time at the back;
- Once the order is determined, don’t adjust it frequently just to make it “read smoothly” – if you change the previous part, you will have to do it all over again later.
Boundary (under what circumstances does this article not hold)
- The implementation and pricing methods of "remember" in different servicesNot the same, the discount range is also determined by the current rules of the platform.
Any mention of specific discounts must be accompanied byEffective Date, otherwise it cannot be recalculated - price figures change frequently, this is not a formal requirement.
- Single call and stateless call cannot be said to be "remembered", and this article has no meaning to it.
- This article does not contain actual measured figures: how much you can save depends on how much stability and dynamics are in your content.Please refer to your revised bill.。
How can you verify it yourself?
Make a comparison before and after the change: press the same paragraphDifferent orderRun it twice (once with stable content first and once with dynamic content first), and then just look at the difference between the two times for the same bill. No tools are required, and no system needs to be plugged into it.
The order variable is free - that's why it's the first one worth touching.
Source and Description
- Source: Tunenomics Tunenomics unified external measurement basis (compare and review date: 2026-09-18).
- This article does not contain original customer data, actual measured figures and savings commitments.
This article is from Tunenomics’ “AI Cost Observation” series. The description of methods and the measurement basis of conclusions in the article can be checked; the numbers are marked with the source, measurement basis and date. Sample data does not represent actual results for any customer.