You can enable analytics to get a better understanding of how your ratelimiting is performing. This is done by setting analytics: true in the options. All data is stored in the same Redis database and writing analytics uses 1 command per .limit invocation. 
const ratelimit = new Ratelimit({
  redis: Redis.fromEnv(),
  limiter: Ratelimit.tokenBucket(5, "10 s", 10),
  analytics: true, // <- Enable analytics
});
Go to the Ratelimit Dashboard and select the database you are using. If you are using a custom prefix, you need to use the same in the dashboard’s top right corner.