rsync.net retains the last 7 days backup (via zfs snapshots) for free though. That's enough retention period for many people. You can add more of you want, but you'll pay for the extra storage usage.
I'd argue it's not enough. If you're using ZFS, you may notice a corrupt file during a monthly scrub. If you're not using ZFS, you may only find out years into the future, when the backups are long gone.
For accidental deletions, 7 days is indeed most likely fine.
