To clarify mesverrum's answer, what they are talking about is the archiveconfig settings which have to do with backing up the data in the database.
The files that appear in your screenshot are the backupconfig files which back up only the settings such as users, rules, groups, etc and NOT the data.
Similarly to his answer, it depends on how far back you want this data. If you want to have a daily backup of your configuration for a month you can delete older files without issue, but you won't have those backups any longer.
You may decide that keeping the configs to a weekly backup makes more sense for you, but you run the risk of not having a backup for settings you may wish to revert to in the future.
Each of these one GB files represents the LEM configuration as it was on that particular day.