The record still holds after close.
Every version, every change and every review decision is written to an append-only trail with who, when and why. Months later, anyone with access can see what the model said on the day it was approved.
Who, when, why
The reason is captured when the change is saved.
Nobody writes a change log by hand. The author, the time and the reason travel with each version, so the record is a side effect of the work.
Decisions on the exact version
A review is recorded against the version it was made on.
A suggestion, a returned review and a sign-off point at the version they judged, so a later edit cannot quietly inherit an earlier approval.
Hand it to whoever asks
An auditor, an LP or a client asking where a figure came from.
Export the audit trail for any model version as a PDF, with a hash chain over its events so a later change to the exported record shows.
See it on your own model.
A thirty-minute walkthrough on a model like yours, with the founding team.