a credit, accredit

A credit or a credit ( two words ) means one ( a ) acknowledgement or attribution--
Is there a credit at the bottom of the photograph?

A credit may mean a sum of money added to an account--
You have a credit of $50 in your account.

A credit may mean a record of academic work completed--
You still need a credit in art or music to meet the graduation requirements.

A credit may also describe a form of payment or payment agreement, or a related check on the solvency of someone--
If you pay with a credit card, you may get a discount.
The property manager will run a credit check before agreeing to rent the house.

Accredit or accredit ( one word ) means to ascribe or attribute to--
Many people accredit him with coining a famous phrase.
To whom should I accredit this quote?

Accredit also means to provide with credentials, as an official or representative, or to certify, as a school or college--
The inspectors will decide whether to accredit the school for another year.
The CEO will accredit him as an official representative of the company.

Now that you know that, you can say--
"If we accredit the image to him, we'll have to add a credit to his acount, as payment for the use of it."