One new issue of The Performance Digest is added every month.
This is a rolling access subscription and not a content purchase.
Because we're continuously adding more issues, and thus more value, into The Performance Digest every single month, we may remove the FREE 7-day trial at any point in time because the amount of value provided simply wouldn't make sense to give away for free.
In addition to this, to match the increase in content and value provided, the cost of a subscription will also increase multiple times per year. However, when you join, you lock in your subscription price for life. After the price has risen, it will never be available again for such a low price.