Can I delete log files once they've been read and reported by S3stat?

Yes. Once we've reported on a day's logs, we don't need the raw files any more.

There is, of course, always the chance that we'll introduce a new feature in the future that pulls additional information from the raw files, and that by deleting those files we wouldn't be able to backfill that feature for your reports. But that's probably not worth packratting 10 years worth of extra logs in your bucket.

You can actually set up a lifecycle rule within S3 to automatically move logs to a lower storage class after a few days and eventually delete them outright. The only reason we don't set this up for you is because it walks a little to close to the line we draw around never issuing a destructive command against your AWS account*.

* There's a small-but-non-zero chance that in setting up that rule you'll accidentally scope it so that it waits until you're on vacation then deletes your entire S3 presence. Our policy is rule out the possibility of being the one who set it up to do that, so I'm afraid we can't offer this as a feature.