Usage-based pricing removes a comfortable fiction: that revenue arrives on a clean monthly cadence just because the product is sold on a subscription. Once product consumption enters the conversation, sales teams and finance teams end up negotiating two different things at once. The buyer wants a predictable number for the CFO, which they can budget with ease. The seller wants an upside on growth. The contract has to hold both.
There are two well-worn shapes for that contract. A prepaid credit pool, drawn down as the customer consumes. Once the customer hits the credit floor, they can't consume the service anymore. Typically used for AI and API services. The second shape is prepaid commitment, with usage trued up against a committed consumption at the end of each period. If the customer exceeds the commitment, they are charged for overage consumption. They look similar on a one-pager, but they land very differently in a billing system, and even more differently inside a Sales pipeline.
Two burndowns, same intent
Both models try to give a buyer a fixed floor and a seller a real ceiling. The difference is risk and growth.
A prepaid credit burndown asks the customer to fund a balance up front. Usage events consume credit balance over the term, and top-ups kick in when the pool is exhausted. The top-up is an active customer decision and the seller can leave revenue on the table before the top-up happens. Revenue recognition smooths the prepayment across the consumption curve. Cash lands early. The buyer carries the unused-balance risk; the seller offers a better price as compensation.
A prepaid commit with overage is more smooth and guarantees the seller growth and NRR. The customer commits to a minimum consumption over a period, pays in advance for the commit, consumes as they go, and is invoiced for any overage when the period ends. Committed cash lands early, overage cash lands late. The buyer carries the risk of paying for something they did not use; the seller carries collection risk for any overage. The larger the commit, the larger rebate the customer gets.
We notice among our users and their customers that the prepaid commit model is universally more liked. The right shape depends on procurement preferences, customer profile, and how confident both parties are in the usage forecast.
The contract is not just a financial artifact. It is the first usage data model a finance team will ever see about a customer.
How Plock shapes the commit side
On the commit side, Plock has a first-class concept built into the subscription itself. Every subscription can carry a minimum commitment — either as an explicit floor, or baked into the first tier of your pricing model as a fixed committed volume. The invoice engine understands it natively: when product consumption for a period lands below the committed volume, Plock automatically closes the gap on the invoice — either with a dedicated minimum-commitment line, or simply by including the first-tier fixed fee.
The product consumption itself is visible in-product. On a given subscription, finance can see:
- The committed floor for each billing period, which also form basis for MRR.
- Measured usage as it accumulates, hour by hour, against that floor
- Whether the period is trending to burn through the commitment or fall short
- The invoice item that will be issued if the customer stays below the floor
Because commitments can be set independently on each line of a subscription through the quote builder, a single contract can carry a commitment on one product and pure overage on another. That matters for customers who want to anchor on a headline product while buying optional capacity elsewhere.
When the period ends, the invoice engine understands if product consumption for the period landed above the committed volume, and Plock renders a dedicated overage invoice item for exceeding volumes.
Scheduled changes and mid-term adjustments
Prepaid commits rarely survive a full year without a renegotiation. Plock lets sales and finance schedule a new commitment floor or pricing threshold to take effect on a specific future date, adjusting the current period's invoice accordingly for any gap. The change drops in automatically at the boundary, and the subscription history records both the previous and the new value. Customer-success teams do not have to remember a manual update.
How Plock shapes the credit side
On the credit side, Plock treats credits as invoice-shaped objects. When a prepaid pool needs to be adjusted, Plock produces a paired credit invoice that mirrors the original — negating each line and linking the two records. The same plumbing that issues a charge can reverse it, which keeps the ledger consistent.
For a prepaid credit deal flow specifically, we recommend modelling the prepaid balance as a fixed fee billed in advance, with a matching consumption-based product alongside it. Plock already supports both advance and arrears billing at the subscription level, and the installments feature on a quote lets a large prepaid purchase be split into a signature invoice and subsequent draws. Overage beyond the commit lands on the same subscription in arrears, which means the customer gets one invoice stream, not two contractual documents to reconcile. Revenue recognition for prepaid and postpaid is automated and synced with your ledger.
Because Plock bills continuously rather than running a single end-of-month script, any overage doesn't need to be an end of period surprise. Usage is processed as it arrives, and the remaining balance reflects reality within hours rather than days.
Where the HubSpot deal lifecycle fits in
The contract is written in HubSpot before it lives in Plock, and Plock is built around that fact. A Plock quote is bound to a HubSpot deal, and the platform keeps deal value and line items in lockstep with the quote as reps iterate. The seller sees the true deal economics on the HubSpot record, not a stale estimate.
When the deal is marked closed-won, a webhook fires and Plock turns the quote into a live subscription — with the right price plan, the right commitment floor, the right billing cadence, and the right invoice interval. The handoff from CRM to billing is not a CSV. It is a state transition.
That same pipeline is what makes both usage-based contract shapes operable at scale:
- A commit quote lands in HubSpot with a consumption-based line item and a commitment marker. On close, Plock creates the subscription with the agreed commitment floor and starts tracking consumption against that volume.
- Mid-term expansion is quoted in HubSpot, synced back as line items, and applied to the subscription as a scheduled change on the agreed effective date.
Which shape for which customer
A quick summary that tends to hold up:
- Enterprise procurement with annual budgets, predictable consumption, and a preference for capex-style purchases tend to favour prepaid commitments.
- Scaling customers with variable adoption curves and a distaste for shelfware tend to favour prepaid credits.
- Most Plock customers end up running prepaid commits, because their buyer base does.
The platform does not force a choice.
Closing thought
The value of a good contract model is boring consistency. A quote agreed in HubSpot becomes the subscription that bills the customer, the ledger entry finance closes against, and the report the CFO reads. When the commitment changes mid-term, every downstream system learns about it at the same moment. That is the posture Plock is built for, whether the burndown runs backward from a prepaid balance or forward from a prepaid floor.
If you are sketching your first usage-based contract or reworking a legacy one, the charging solution page walks through how the pieces fit together, and the team is happy to look at your specific deal flow on a short call.