When running a database in FULL recovery mode it is required to take regular LOG backups. Without running LOG backups the space inside the LOG-file can not be re-used and results in a full file (when max growth is set) or results in a full disk.
FULL recovery is required if you need to be able to restore the database to a specific point-in-time. If this requirement is not necessary for your database, consider changing the recovery model to SIMPLE.
So, schedule regular (every 15 - 180 minutes depending on the activity of the database) LOG backup or change the recovery model of the database to SIMPLE.
** Don't mistake the ‘stupidity of the crowd’ for the ‘wisdom of the group’! **