There isn't a clear cut definition of what is considered abuse, but usually it's pretty clear cut. Abusers typically make many posts a day with no real content, often on multiple accounts, and use bots to constantly upvote all of them.
If you are writing actual content and using the bots to promote it you should not have any problem and you can use them more than once a day.
ok, great. Thank you. I wanted to make sure that as long as I was making a good post, that I could use any number of bots.