Pay-as-you-go
Keep working past your monthly allowance, with a spending cap you control.
By default, when you use up your monthly allowance, Clusy drops you back to the free Auto-on-CPU loop until the next cycle, so you keep working but without the metered extras. Pay-as-you-go is the optional alternative: keep using the metered models and runtimes past the allowance, billed for the overage, with a cap you set so it can't run away.
How it works
Turn it on in Settings → Billing and set a monthly cap, the most you're willing to spend beyond your plan. With it on, you keep working uninterrupted when the allowance runs out, overage is billed on top of your subscription, and spending stops at your cap. Once you hit the cap, metered work stops and you're back on the free Auto-on-CPU loop, the same as it would be without pay-as-you-go.
The cap is the point. It's not an open tab. It's "let me go up to this much, no further."
Guardrails
Two limits sit around it. Your monthly cap is the ceiling for the whole billing period. A per-run limit caps how much any single run can spend, so one runaway loop can't burn the whole cap at once. Together they cover both the slow drift of lots of usage and the sudden spike of one expensive mistake.
Who can use it
Pay-as-you-go is a paid-plan feature, since it extends an allowance you already have. It isn't offered on the free tier, which has no allowance to extend. There, the way to more metered usage is to upgrade.
Set the cap to a number you'd be fine paying
Treat the monthly cap as the amount you wouldn't mind being charged this month. Set it there and you get the convenience of never being interrupted mid-task, without an open-ended bill.
Switch it off any time in Settings → Billing. The free Auto and CPU loop keeps working either way.