Start with the decision
A renewal metric is useful only when its denominator and time window match the decision in front of you. Finance may need gross revenue renewal, while a customer team needs account-level renewal by due month. Publishing one blended rate can hide both contraction and customer loss.
Keep due and observed populations separate
Customers eligible to renew belong in a due-based view. Customers who happen to be active at month-end belong in a stock view. Mixing these populations makes short-term movement difficult to interpret, especially when annual plans and grace periods are involved.
Create a metric contract
Document the eligible population, renewal event, grace period, currency treatment and exclusions. Then show at least one segmented view beside the headline figure. A shared definition prevents meetings from becoming debates about whose spreadsheet is correct.