A media pricing flag sits on a revenue path, so the cheapest-looking control plane can become the expensive choice when nobody can explain which variant produced an invoice. I would choose between an analytics-integrated flag service and a standalone flag API by measuring attribution work, not by comparing the smallest advertised plan. The winning shape is the one that gives the server a stable decision, attaches that decision to the pricing event, and does so without turning every reader or article into a metric label.

TL;DR: evaluate the pricing flag on the Node.js side, return the resolved variant with the price response, and emit one low-cardinality decision counter plus a trace or structured event carrying deeper context. An analytics-integrated system reduces glue when flag exposure and product analysis belong in the same data path. A standalone API keeps the control boundary smaller when another pipeline already owns events.…