MRR movements explain why MRR changed, new business, expansion, contraction, churn and reactivation, each by customer.
MRR at month end = MRR at month start + new + expansion + reactivation − contraction − churn (+ exchange-rate effect)
New business is a customer's first recurring revenue. Expansion is an existing customer paying more (upgrade, more seats, a discount that ended), contraction paying less. Churn is a customer going to zero, reactivation a churned customer coming back.
A plan switch is one movement. Cancelling one subscription and starting another on the same day is an upgrade or a downgrade, not a churn and a new customer.
Every movement in sumwerk names its cause and the Stripe invoice or event it was derived from. The effect of exchange rates is a line of its own, never a movement.
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.