Backup space not available even if only one backup was done a long time ago

I'm trying to backup my devices and I receive an error message: No space left on server for backup.

My account has only one backup for one of my devices from 6 months ago. I have three devices from five licensed. How many backups is suposed to be permited? Or how many contacts each device can backup?

Does Symantec Servers has not enough space for customers backups? Should I move to a different app?