The short answer
Use MMM to distinguish new subscription acquisitions from automatic billing and active retention events. Estimate incremental acquisitions, then value them using cohort customer lifetime value and an explicit payback target. Keep recurring revenue in the business forecast, while preventing the same future payments from being counted twice in marketing's contribution.
This article is part of Asked by Marketers, a series answering real questions from marketing leaders.
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Why marketers ask this
A subscription business can collect substantial revenue this month from customers acquired long ago. Meanwhile, a campaign that brings in valuable new subscribers may generate little immediate revenue. If the measurement treats every payment as the same kind of sale, the acquisition team can struggle to see which channels are growing the customer base and how quickly that growth pays back.
What should count as a subscription acquisition?
Define the customer action you want advertising to cause before choosing the model's outcome. A new subscription, an active contract extension, and an automatic monthly payment carry different information about demand.
Start with the events in your subscription system. Agree what makes a subscription valid, which product it belongs to, and whether the customer is new to the business or only new to that product. An existing mobile customer buying broadband, for example, is an acquisition for broadband even though the person already has a relationship with the company.
| Event | Question it can help answer |
|---|---|
| A customer starts a new subscription | How many additional subscriptions did advertising acquire? |
| A customer actively renews or changes a contract | How much did relevant activity contribute to retention or a product change? |
| A scheduled payment is collected automatically | How is revenue from the existing subscriber base developing? |
Keep those definitions stable in the data feed. A change in how upgrades or renewals are classified can change the apparent acquisition trend even when customer behavior has not changed.
How should MMM treat automatic renewals?
Keep automatic renewal revenue distinguishable from new acquisition outcomes. It can be part of a broader revenue analysis, but its presence in the same week's sales does not establish that this week's advertising caused it.
Marketing Mix Modeling can use separate outcomes for new and returning customers. For a subscription business, those labels need an additional check: does “returning” mean someone actively chose to buy again, or that the billing system collected a scheduled payment? The answer determines what the model is being asked to explain.
For acquisition planning, a model of new subscriptions gives the team an outcome tied directly to its task. If the business also wants to measure retention activity, define the relevant retention event and supporting data separately. Automatic billing does not prove that marketing has no influence on retention; it means billing alone does not describe that influence.
Reconcile these views with total subscription revenue. The acquisition report and the revenue forecast serve different decisions, so their totals need not be identical. The relationship between them should be clear enough that finance can follow a cohort from acquisition into later payments.
How should we value the subscribers MMM attributes to marketing?
Apply a consistent customer-value estimate to incremental acquisitions. This lets the budget decision account for differences in renewal behavior and customer value that an acquisition count alone misses.
Use cohorts that preserve meaningful differences, such as acquisition channel, product, and acquisition month. Choose a value horizon explicitly. An annual subscription and a monthly subscription may collect revenue on very different schedules, even when both create a valuable customer relationship.
Keep observed cohort performance separate from predicted future value. Recent customers have not yet had the opportunity to renew over the full horizon. If their value is predicted, make that visible alongside the acquisition estimate.
The Full iROAS framework explains how incremental acquisition and future value can inform a broader return measure. For subscriptions, check which payments are already included. Adding a customer's full predicted value to a sales contribution that already contains some of those payments would count that value twice.
Where feasible, use incrementality testing to check the acquisition outcome. A test of sign-ups supports a different conclusion from a test of total revenue, particularly when most revenue comes from an established subscriber base.
How should payback affect the budget decision?
Set a payback requirement alongside the customer-value horizon. A channel can acquire profitable customers and still consume cash for longer than the business can support.
Agree whether the decision uses revenue or contribution after relevant variable costs. Then assess when the acquired cohort is expected to recover its acquisition cost. Two channels with similar eventual value can create different cash demands because their customers pay, renew, or cancel at different times.
The payback requirement belongs in the business decision. It should not be achieved by changing model assumptions until acquisition costs match a preferred target. If a channel misses the required payback period, the team needs to decide whether to constrain its budget, improve its economics, or accept a longer recovery period.
How this looks in practice
Consider a hypothetical subscription business comparing two channels. Assume the incremental acquisition estimates are credible and both cohorts are valued using contribution before acquisition cost over the same 12-month horizon. The figures below are illustrative, not customer results.
| Measure | Channel A | Channel B |
|---|---|---|
| Advertising spend | $10,000 | $10,000 |
| Incremental subscriptions | 100 | 80 |
| Cost per incremental subscription | $100 | $125 |
| Expected 12-month contribution per subscription | $180 | $250 |
| Expected acquisition-cost payback | 4 months | 8 months |
Channel B produces fewer acquisitions but more expected cohort contribution: $20,000 compared with $18,000. If the business requires payback within six months, Channel A meets that requirement and Channel B does not. The timing estimates are separate assumptions; they cannot be calculated from the 12-month totals alone.
Revenue collected from older subscribers remains in the business forecast. It is not added to either channel's new-acquisition result simply because the payments arrived while these campaigns were running.
How Sellforte helps
Sellforte can model acquisition outcomes separately from revenue and connect incremental acquisitions with customer-value data. The outcome definitions, value horizon, and payback requirements should be agreed as part of the measurement setup. Book a demo.
Authors
Lauri Potka is the Chief Operating Officer at Sellforte and has over 15 years of experience in Marketing Mix Modeling, marketing measurement, and media spend optimization. Before joining Sellforte, he worked as a management consultant at the Boston Consulting Group, advising some of the world's largest advertisers on data-driven marketing optimization. Follow Lauri on LinkedIn, where he is one of the leading voices in MMM and marketing measurement.