What one check is

One check is one question sent to one engine, one time.

That is the unit everything in Keylight is counted in. A question tracked on three engines is three checks each week. Forty questions on three engines is 120 checks a week.

Questions are never sent everywhere automatically

A question is only ever asked on the engines you chose for that workspace. Nothing fans out to all eight on its own, because that would spend your capacity four times faster than you expected.

What a check includes

The question being asked, the full answer being stored, the sources being recorded, the brand and competitor matching, the discovered brands being read out, and the answer being kept for as long as the workspace exists.

All of that is one check. There is no separate charge for reading an answer again, which is why competitors and discovered brands cost nothing extra.

Why the unit matters

Because it makes your bill predictable in a way a per-keyword price is not. You can work out exactly what a workspace uses: questions, times engines, every week.