How could they stay on free dynos? You can't be running on a free dyno 24/7. It's like 16/7 or something.
Heroku could have gone back to that i suppose, instead of getting rid of free dynos entirely, but they didn't.
Still... I think you could basically only run one free dyno per account 24/7. I am curious if they somehow fit their entire production in one free dyno, or were somehow splitting things between multiple accounts, or what.