No, but if you have that many you probably have PHP/SQL errors going on constantly and it's logging them. Check it for warnings/errors then fix them if fixable. Otherwise you can prune it manually by emptying the table from phpmyadmin every now and again. Normally it should not fill up that quickly.

Ok, two things. First, I misread the number and it is 46,000 entries not 460,000. Second, there are only 110 errors. The rest are just informational or what is considered 'change log'. Do I have some type of debugging turned on by mistake where it is logging everything?

I see, this is normal then. It logs all of your changes within CBSubs so you have a history of changes made. Everytime you edit and save your plan and something has changed it logs a history entry for it. Same for plan purchase process, etc..

And at what point are the number of records in this log table going to start affecting the performance of my database?

Probably never, the auto increment column can support well over a billion entries. The history table never does full lookup anywhere except in CBSubs > History. In all other cases it's just an insert, which is very fast.

Any suggestions for automating the cleanup of that table so I don't need to babysit it?

You shouldn't need to baby sit it. Just clear it say once a year or every 6 months, etc.. You maybe able to setup a CRON task to empty the table periodically.