Most product subscriptions are one of three structures, and they behave differently enough that picking the wrong one costs you years of fighting your own model. Replenishment bills for something a customer consumes and reorders. Curation ships a changing selection you choose for them. Access charges for continuing entry rather than a shipment.
Replenishment models
Replenishment fits products with a predictable burn rate: coffee, filters, supplements, pet food, razor cartridges. The customer already repurchases, so you are removing a chore rather than inventing a new want. The real design work is matching the interval to actual consumption, because shipping faster than people use the product is a common cause of early cancellation. Offer interval choice at signup and keep it editable.
Curated box models
Curation sells discovery, so your taste and sourcing are the product rather than any single item. These programs carry higher content costs and shorter average tenure, because novelty fades once a subscriber has seen the range you can source. They work best where variety is genuinely deep: snacks, coffee origins, candles, stationery, craft or hobby supplies.
Access models
Access charges for standing benefits attached to your store: member pricing, included shipping, early access to drops, a monthly credit or priority support. Nothing physical ships on a schedule, so margin is cleaner and fulfillment risk largely disappears. The risk moves to perceived value, because subscribers mentally compare the fee against what they actually bought that month.
Action Step
List your three best-selling products. Beside each, write how often a typical customer rebuys it and whether that next purchase is predictable. If two or more are predictable, start with replenishment. If none are, design an access model instead.
This lesson is educational and reflects general practice. Results depend on your situation, market and effort; adapt what you learn to your own context.