I currently have an app deployed on Heroku which runs on two web dynos so it won’t go to sleep if it remains inactive for a certain time.
Now if I scale it down to only one web dyno (free) and instead pay for one worker dyno, will Heroku always keep my app active?
It will still idle – you NEED to have more than a single web dyno
https://devcenter.heroku.com/articles/dyno-idling