01In plain English
With usage-based pricing the bill follows your activity. A voice agent might charge per minute, a support bot per resolved conversation and an automation tool per task run. Some plans add a small base fee on top.
02Why it matters when you are choosing
It can be the cheapest option when you start small and the most expensive once volume grows. A busy month means a bigger bill, so it is harder to budget for than a flat plan.
03What to check
Ask the vendor
Estimate a normal month and a busy one, and check whether you can set a spending cap or get an alert before the bill jumps.