What happens to existing subscriptions when an offer changes?
Short answer
They follow it. A change creates a new version of the offer, and every subscription on it is billed under that version from its next charge. Before saving, your merchant sees how many subscriptions are affected and confirms. Past orders keep the version they were charged with.
In detail
They follow it.
A new version per change
Each edit is saved as a new version of the offer, with its date.
Impact shown first
Before anything changes, the console shows how many subscriptions the new version reaches, and the merchant confirms.
History untouched
Orders already charged keep the version they were billed under, so reconciliation and reporting stay intact.