How to deal with heroku pricing?

Question

Heroku

I can't figure out how heroku pricing works.
Let's say I bought the "Hobby" plan ($7 per dyno/month):

• What is "dyno/month"?
  
• If I run one web process that runs for exactly one month, will I pay exactly $7?
  
• What if I want to run this process in two threads? Then I have to pay $14?
  
• What if I have two different processes? Let's say one web and one worker, and both worked for exactly one month.
  

Answer 1

practice
there is free dyno, test