A restatement is a dated record that a closed month's figures changed, with the reason, the figures before and after, and the customers behind the difference.
The past of a subscription business does change: late data from the billing system, two billing accounts that turn out to be one company, a changed reporting currency. The problem is never that a number changed, it is that it changed silently.
sumwerk records a restatement before it shows the new figures, points at it on the overview, mails the account's owners and can notify your own reporting.
A restricted, read-only key is all it takes. The first import runs in a few minutes; every number you see opens into the customers and Stripe references behind it.