The amount you repay will be pre-agreed with the lender and will be taken as a percentage of your card sales. Due to it being a percentage, the amount will fluctuate depending on how busy or quiet you are. 

As an example, if you agree that the lender can take 20% of each sale through your card terminal, it could look something like this: 

Customer 1 spends £20. Therefore, the repayment to the lender will be £4.

Customer 2 spends £500. Therefore the repayment to the lender will be £100. 

Customer 3 spends £75. Therefore the repayment to the lender will be £15.

This process happens automatically, so you can repay the funding without having to work out your finances and save for a fixed date each month.