Store - Subscription - Credits Edit
Currently in the store you can purchase team icons, monthly subscriptions and additional credits.
You can purchase Weekly, Monthly, 3 Monthly or 1 Year subscriptions. The revenue of subscriptions go towards developing the game and improving it for the future. It also gives you a cool looking badge and tells other people that you're a subscriber and supporter of the game long term.
Credits is the currency that they are using to purchase additional items to make your team look pretty, stand out. You also use credits to purchase the subscription you would like.