Answer: The easiest way is to regularly use the Foxhound1 - Tools - Backup Foxhound Database shortcut which will backup and restart the active Foxhound transaction log file, keeping only the three most recent backups and discarding older copies.

You can automate this task; see How do I backup my Foxhound database on a regular basis?

See also...
Foxhound Help - Controlling Growth
Foxhound Help - Backup and Restore
How do I keep the Foxhound database file from growing so large?