promo

A promo moves the price of entry, in public, for everybody who joins during the window. That makes it a different instrument from a limited offer, which puts a deadline on one piece of content inside one private conversation, from cutting the price of a paid file, which changes what a buyer pays rather than who arrives, and from a free trial, which gives the entry away entirely for a few days. A promo is an acquisition lever pointed at the entry fee, and the entry fee is usually the cheapest thing an account sells (pricing your content covers where it sits).

What does a promo actually bring in?

Conversations, mostly. A subscription is the floor of an account’s revenue rather than its total, so cutting that floor for a month and filling it with new arrivals produces a modest amount of money and a large amount of inbox. That is the honest description of the trade-off: you are buying reach into private threads at a discount on the entry fee.

Which means the promo is worth exactly what happens afterwards. A hundred new subscribers nobody has time to write to is a smaller result than ten who get answered.

Who does a promo bring in?

People for whom the price was the obstacle, which is not the same population as the fans who paid full price without hesitating. Nothing about that is disqualifying; it is simply a reason to keep the two groups apart in your reporting instead of averaging them into one base.

• Track the promo intake as its own group. Cohort analysis is the tool, and the promo month is the natural cohort boundary.
• Compare it against a normal month’s intake, on the same measures: who replied, who bought, who was still there in month two.
• Judge it on the second month, not the first. Everything looks good in the first.

What does a promo do to renewal?

A promo sets up a price change the fan did not choose. The discounted rate applies to the window; what he is charged when the window closes is a platform setting, and it is worth reading before the promo runs rather than after the first complaint. Either way the account faces the same moment: a group of subscribers who joined at one number facing another.

That moment shows up in churn and retention a month later, which is why a promo cannot be evaluated while it is running. The subscriber count during the window is the least informative number the promo will ever produce.

When is a promo the wrong lever?

Three cases, and they cover most of the disappointing ones.

Situation	Why a promo makes it worse
The inbox is already behind	More arrivals, same hours, slower replies
Fans leave after month one	The problem is retention, not the entry price
Promos run every month	The discounted price has become the price

There is a fourth, subtler failure. A promo produces a rush of new threads, and a rush of new threads produces the temptation to sell in the first message. Our data puts a pitch before the sixth message at roughly a third of conversion lost, with the optimum after about ten real exchanges. The discount buys the threads; pitching into them on message one throws away what the discount bought.