Comment 2 for bug 1167491

This sounds like you don't/didn't have it marked as a startup application. Launching the 'Startup Applications' program and making sure the BitBudget entry is ticked should fix this.
The 'base' of the units refers to how prefixes are used. Base 2: 1GiB = 1024MiB = 1024KiB = 1024B. Base 10: 1GB = 1000MB = 1000KB = 1000B. If in doubt, use the default, which is base 2.
The icon issue was an oversight and I have filed a separate bug: https://bugs.launchpad.net/bitbudget/+bug/1171639.
The issue in the comment is an issue with one of your repositories and the triangle icon is from the update manager. I'm not sure what would cause this - it may be a temporary server issue.

To help with diagnosis, please upload copies of the following files if they exist:

    ~/.config/bitbudget

    ~/.config/autostart/bitbudget.desktop

'.config' is a hidden folder in your Home folder - to view it you can press ctrl+h in the file chooser or file manager.

Some technical details: in order to track data usage, BitBudget uses a background 'daemon' program. In order to start this when you log in, BitBudget registers this daemon with the FreeDesktop.org autostart system. Desktop environments such as Unity, Gnome and KDE use this to launch programs when you log in. If they are misconfigured, if a user chooses, or if other misbehaving applications interfere with this system, some startup applications may not launch.