Every ISV is already running a second business inside the first one.
Customers use the software to run their operations, and those operations move money. Invoices get paid. Memberships renew. Bookings get charged. Every one of those transactions generates revenue for someone. The only open question is whether any of it comes back to the platform that made the transaction possible.
That is the starting point of ISV economics. Payment monetization is often treated as a product decision, a feature to ship when the roadmap allows. It is better understood as an economic decision, because it changes not just how much a software business earns but what that business is worth.
The three layers of ISV revenue
Most vertical software companies earn in two ways.
The first is license and subscription revenue. It is predictable and it is the foundation of the business, but it grows in only two ways: adding customers or raising prices. Both take time, and both have limits in a defined vertical market.
The second is services revenue. Implementation, training, custom work. It is real money, but it scales with headcount. Every additional dollar requires additional hours.
The third layer is the one most ISVs have not built yet: transaction-based revenue. Embedded payments revenue behaves differently from the other two. It does not depend on a renewal conversation, a price increase, or a new logo. It grows when your customers grow. A merchant that processes more volume this year than last year generates more revenue for the platform automatically, with no incremental sales effort and no incremental headcount.
That difference in behavior is what makes the third layer worth studying. It is the only revenue line in the business that compounds with customer success by default.
The ARPU math
The most direct way to see the effect is through average revenue per user.
For a pure subscription business, ARPU is essentially fixed between pricing changes. The number moves when the price sheet moves, and price increases carry churn risk, especially in vertical markets where customers talk to each other.
Payment monetization lifts ARPU through a different mechanism. When payments run through the platform, every account contributes revenue in proportion to the volume it processes. The subscription line stays exactly where it was. On top of it sits a second stream that expands as the customer transacts more, adds locations, or grows their own business.
The compounding effect is the part that tends to get underestimated. Subscription ARPU is flat by design. Payments ARPU has a growth rate attached to it, because it inherits the growth rate of the merchants underneath it. Over a multi-year horizon, the gap between an account that only subscribes and an account that subscribes and processes becomes the single largest driver of revenue expansion in the business.
Why boards and acquirers price payments revenue differently
Platform valuation is not a function of revenue alone. It is a function of revenue quality, and revenue quality is judged on a few consistent dimensions: durability, growth, margin, and retention.
Payments revenue scores well on all four. It is recurring in practice, because it is tied to the daily operations of the merchant rather than to a contract anniversary. It is usage-based, so it carries built-in growth. And it is unusually sticky, because moving payments means disrupting invoicing, reconciliation, and cash flow, which is the last workflow any operator wants to touch.
The effect shows up most clearly in net revenue retention. A software company whose accounts expand through processing volume can post NRR above 100 percent without selling a single upgrade. That is the metric sophisticated buyers and boards watch most closely, because it separates businesses that grow by replacing lost revenue from businesses that grow on top of a base that is expanding on its own.
This is why two ISVs with identical top-line revenue can be valued very differently. The one with a monetized payments layer has a stream that is more durable, faster growing, and harder to displace. Markets consistently pay a premium for that profile.
The fragmentation tax
There is a common objection at this point: many ISVs technically already earn something from payments, through a referral arrangement or a patchwork of processor integrations. So the layer exists, the thinking goes, even if it is thin.
The problem is that a fragmented setup does not just earn less. It leaks. Margin flows to third parties, transaction data scatters across systems that do not talk to each other, and the merchant relationship sits partly outside the platform’s control. We covered the full cost structure of this pattern in The Hidden Cost of Fragmented Payment Integrations in Vertical Software, but the valuation point is simpler: revenue that leaks out of the platform never makes it into the multiple. Fragmentation does not just cost margin today. It costs enterprise value at exit.
Run the numbers on your own platform
The concepts above are general, but the decision is always specific. The right way to evaluate payment monetization is not to take the industry’s word for it. It is to model your own merchant base, your own volumes, and your own economics.
For Constellation Software and Jonas operating companies, CSIPay was built to make that layer available without building payment infrastructure from scratch. If you want to see what the economics look like for your platform, reach out to run the ISV economics model with our team. The math is usually more compelling than the summary.