Here's a business that doesn't have much of an "anniversary" effect ... look at months = 11/12 ... incremental rebuy rates don't change a whole lot (they improve marginally).
This business does possess an interesting dynamic. Notice how incremental rebuy rates at month = 2 are higher than at month = 0.
Also notice how incremental repurchase rates don't dip under 1% until the customer has lapsed bast about eighteen months.
This is the life table from a credible catalog brand. The cataloger leverages catalogs to encourage cross - shopping across departments. Even after twelve months of recency, the customer is still responsive.
E-commerce brands that have highly credible email marketing programs exhibit comparable dynamics.
If incremental repurchase rates dip under 1% prior to twelve months of recency, it is possible that your marketing program isn't very solid.