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You sell one or more tiers. Each costs something, and each includes something. You build that in the dashboard, and it looks like what it is — there’s nothing to learn here. What the dashboard can’t show you is what happens on the day you change it.

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Changing your offer without changing your customers

Say you raise the Pro tier’s limit from 200 to 500, and add a feature to it. Two things could happen:
  • everyone already on Pro is quietly moved to the new terms, or
  • they keep what they signed up for, and only new customers see the change.
Both are legitimate. A phone carrier usually leaves existing customers on their old plan when the lineup changes; a car insurer reprices everyone at renewal. What’s not legitimate is the third option — finding out which one happened after it happened. So Kerne makes the safe answer the default. When you change what a plan includes, that change reaches new subscribers only. Everyone already subscribed keeps exactly what they had, indefinitely, until you deliberately move them.
Each time you change what a plan includes, you publish a new version of that offer — a pack in the dashboard. A subscription is attached to the version that was current when it started, and stays there.
Your code never mentions a version. allows(), check() and entitlements() resolve through whichever one the customer is on.

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Moving someone to a newer version

Two things do it, both deliberate:
  • They change plan. Switching plans re-attaches the subscription to the target plan’s current version.
  • You migrate them. From the dashboard, on purpose, when you’ve decided the old terms should end.
Nothing else moves a customer. A price change, a new feature, a raised limit — none of it reaches someone already subscribed.

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What happens when a payment fails, or they cancel

Two moments need a decision from you, because the obvious answer isn’t obvious. Both are set per product in the dashboard.
End of period by default — access continues through what’s already been paid for, and stops when that period ends. An explicit immediately flag on cancel() cuts access right away instead. That’s a per-call choice, not a stored setting.
Nothing happens by default — Kerne never automatically cuts access over a failed payment. The subscription sits at PAST_DUE until the provider resolves it.Or: block after a grace period — the customer keeps access for a number of days you set, then a background sweep moves them to UNPAID, which does cut access, if nothing was paid by then.
PAST_DUE and UNPAID are subscription statuses — see the subscription shape for the full list. A downgrade to a cheaper plan applies immediately today; there’s no end-of-period option yet.

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Next

Entitlements

What an offer actually grants.

Pricing models and meters

Flat, metered, and what a meter measures.