How to find which channel buys customers who actually stay

A subscription app optimized everything for cost per signup. Their cheapest channel won every report. But churn ate the gains and nobody connected the two.

The lifetime-value playbook:
— Tag each user's acquisition source on first session
— Build a cohort of each source's users from one month
— Track their cumulative revenue out 90 days, not day one
— Divide 90-day revenue by acquisition cost per source
— Re-rank channels by lifetime value, not signup cost

The cheap channel's users churned in week three, returning $14 each. A pricier channel's users stuck around and returned $58 over 90 days, more than triple the value despite double the cost.

They reallocated toward the higher-LTV source. Cost per signup rose, but 90-day revenue per dollar climbed 40%.

Lesson: cheap signups and valuable customers are rarely the same people. Measure who stays, not who's cheapest to acquire.