Every translation uses AI tokens: the text sent to the model and the translation that comes back. We convert those tokens into credits at the price of the model you choose, so one credit always buys the same amount of AI work.
You pick the model per store in the Magento admin: a larger model uses credits faster, a small one (Claude Haiku, GPT nano) only a fraction; short, repetitive fields are batched together and cost very little. The Estimate button in the Magento admin shows the expected credits before you translate, and your dashboard shows the real number for every request.