All the benefits of Pro Plan are listed in the pricing page (https://www.runcomfy.com/pricing), including 200GB storage, $10 monthly credit and 20hrs Free CPU machine, etc.
RunComfy doesn't have a soft currency that measures in "credit", once you subscribe, our billing system automatically credit your account with $10. For $10 you will get, say for 24GB VRAM Large GPU machine with Pro Plan which is priced at $1.39/hr, $10 / $1.39/hr ~= 7.2(hours). You can find all unit price for different machine sizes on the Pricing page (https://www.runcomfy.com/pricing).