Overview
On-demand usage is a pay-as-you-go option for all AI features in Heptabase. Once your free credits and included plan credits are used up, you can enable on-demand usage to keep using AI features and pay based on actual usage.
How do I enable it?
Go to Settings → AI features and enable on-demand usage. You will then be asked to set a monthly spending limit, which officially activates it.
How does billing work?
On-demand usage is billed based on actual usage. It is not a prepaid package of credits. You do not buy a fixed batch of extra credits in advance. Instead, you use AI first and are charged afterward based on what you actually used.
Billing is triggered in two situations:
your running on-demand total reaches $10, or
your billing cycle ends, at which point any remaining unpaid usage is charged.
When the $10 threshold is crossed, the AI interaction that pushes you over generates an immediate bill for the running total at that moment (≈ $10) and charges you right then. Your counter then resets to $0, and the same rule applies again from there — the next charge is either when it hits $10 again, or whenever the cycle ends.
Example: your reset day is the 20th, and you start using on-demand on the 12th.
Scenario A — under $10 by cycle end: by the 20th, you've used $8.50 in total. You're charged $8.50 on the 20th when the cycle resets.
Scenario B — crosses $10 mid-cycle: on, say, the 16th, an AI interaction pushes your running total just past $10. That interaction itself triggers an immediate bill for ≈ $10 and your counter resets to $0. You keep using AI from the 16th to the 20th and accumulate, say, another $2.50. That $2.50 is then charged on the 20th with the cycle reset.
What does the monthly spending limit do?
The monthly spending limit caps your additional on-demand charges for the month.
For example, if your limit is set to $10, your pay-as-you-go charges for that month will stay at or close to $10.
Note: an AI interaction that crosses your spending limit will still complete, so the final charge may go slightly above the cap. After that point, on-demand usage is paused until your next billing cycle.
Does on-demand usage expire each month?
No. On-demand usage is not a monthly bundle that needs to be used up. It is simply pay-as-you-go billing for additional AI usage. You are charged only for what you use, up to your monthly spending limit.
Can I top up extra credits in advance?
No. On-demand usage is not a prepaid credit pack — there is no way to buy a bundle of credits ahead of time. You only pay for what you actually use, up to your monthly spending limit.
Do unused monthly plan credits carry over to next month?
No. Plan-included credits reset on each billing cycle and do not accumulate. For more on how plan credits work, see Pro, Premium and Premium+ Plans: Pricing & FAQ.