A company's application runs on Amazon EC2 instances.

To analyze and find the number of logins for a specific user from the past 7 days, a CloudWatch Logs Insights query is the most suitable solution. CloudWatch Logs Insights enables you to interactively search and analyze your log data in Amazon CloudWatch Logs. You can use the query language to perform queries that contain multiple commands, including aggregation functions, which can count the occurrences of logins for a specific username over a specified time period. This approach is more direct and efficient than creating a metric filter or subscription, which would require additional steps to publish and sum a metric. References: AWS Certified DevOps Engineer - Professional, CloudWatch Logs Insights query syntax, Tutorial: Run a query with an aggregation function, Add or remove a number widget from a CloudWatch dashboard.