Credit Cards have a spending limit. This limit is the amount of money in which the credit card company will allow you to use.
When you buy something, the limit is consumed. When you pay for the invoice, the limit is released.
Let's suppose you have $2500,00 of limit approved by your credit card company and you buy $1000,00 on 4 installments. That means you will have $1500,00 available on your credit card to spend after this purchase. Remember: the value consumed is the total value of the purchase, not the value of the installments.
When you pay your invoice of $250,00 (the first installment), your available limit will be now $1750,00. That means the value of the paid invoice is returned to the credit card limit.
With this feature, you will always be able to know how much you have available on your credit card on Mobills.
You can check details about Credit Cards on each platform: