# Lots and Consumption Window On The Grid, purchased Units are grouped into Lots when they enter your Consumption Account. Each Lot has a 4-hour Use It or Lose It window: tokens not consumed within that window expire permanently. \ \ This perishability is a deliberate design choice - it gives suppliers confidence that demand is real and near-term, which lets them price aggressively, and it prevents capacity hoarding that would distort the market. ### What are Lots? When Units leave your Trading Account, either through a [Scheduled Sweep](https://thegrid.ai/docs/introduction/core-concepts/scheduled-sweeps) or a voluntary transfer, they are grouped into **Lots** in your Consumption Account. Each Lot: * Represents a **specific quantity** of Units. * Has a fixed **4 hour expiry**. * Is consumed on a **first in, first out (FIFO)** basis. The system always spends from the Lot that expires soonest. ### Why 4 hours? The 4 hour window is a deliberate design choice: * It gives suppliers strong certainty that any Units they sell will either be used quickly or expire, which lets them price more aggressively and predictably. * It is long enough to cover typical interactive usage and near term batch jobs, including workloads scheduled around predictable troughs. If a Lot reaches the end of its 4 hour window with leftover tokens, those tokens expire and are no longer usable or refundable. This use it or lose it rule is a core part of the market discipline. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://thegrid.ai/docs/introduction/core-concepts/lots-and-consumption-window.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.