Last backup

Hello All,

I have a backup at a site which closes, this week I will do a last backup. I know that I can change the retention if I want. But I went into a discussion with a colleague. He said in other backup software the last backup is kept forever. I don't know how Netbackup handles the last backup.

Or for example, when a week backup with a retention of one month is made this backup is kept until the retention time expires with an exception when there is no other new week backup or other full backup this week backup will be kept forever until there is a new full backup made. OR is the week backup in my example deleted when it expires?

Rob