I came across the offer by Heroku that says that I can receive free 450 dyno hours for just adding my credit card. I was wondering how the free hours are added. Are they like the standard 550 hours, i.e. added every month or is it just for one time?
Also I just want to run one dyno and so having 1000 total hours per month would be more than enough. So if they add 450hrs/month with the credit card, does that mean I can run my dyno infinitely without being charged at all?
Yes, correct you will get 1000 dyno hours once you verify your identity with a credit card. For a single APP they are enough but in case you want to add more APPs, allowed dyno hours will be sum of hours consumed by each APP. Initially 550 hours were provided to keep the APP active for 75% of time i.e. 18 hours (18*30 ~= 550).