Retrofitting Billing Enforcement Into a Product That Already Shipped Features

It's common, especially early on, to build product features faster than the billing enforcement around them. The priority is proving the product works, and gating gets treated as a later concern. Eventually someone has to run the uncomfortable audit: which paid-tier features are actually enforced, and the honest first answer is usually "not all of them." A real retrofit pass added genuine per-tier feature gating with upgrade prompts where access was previously unrestricted, built a proration flow for plan upgrades with revised usage limits, and specifically gated downloads and license enforcement to paid subscribers, closing off functionality that had shipped and been fully usable by anyone, including free-tier accounts, up to that point. The framing that made this move fast: unbilled access to a paid feature was treated as a launch-blocking bug, not a backlog item, once there were real paying customers, because every day it stayed open was actively costing revenue, not just a theoretical gap. The audit method itself is straightforward and repeatable: go through the pricing/plan table feature by feature, cross-reference each one against the actual code paths that gate (or fail to gate) it, and flag anything reachable by an account on a lower tier than the feature requires. If you're past MVP and taking real payments, run this audit now rather than waiting for a support ticket or a revenue review to surface it for you.