How do I host my discord.py bot on heroku?

You're missing a couple of things to make this work, for the sake of everyone Googling how to host discord.py on Heroku and getting this as the top result here's a step-by-step

1. Install Git and do git init when inside your directory
2. (If you're using virtualenv or similar go into it and) do pip freeze then copy the contents you get to a file called requirements.txt and save it in the same repository as the bot

3. Make a file (a file of type file) , open it with notepad and write worker: python name_of_bot_file.py and save within the same repository

4. Make a text file called runtime.txt and paste python-3.6.5 or whichever python version you were using to write the bot and save it in the same repository.

5. (If you're inside virtualenv get out and) open your console and write heroku login and input your heroku login details

6. Then do heroku apps:create name_of_app and heroku buildpacks:set heroku/python

7. Finally, do git push heroku master or git push heroku branch_name:master if you want to only push one branch

your procfile isn't right. a web application(web:<command>) is for websites (which your bot isn't). the right one is worker: python3 bot.py.

Also, you need a requirements.txt. inside the file, write every module you need to download. in your case, its just discord.py.