Your compounds generate Credits, depending on its gene, its size and the level of the mutants placed on it.

To get the Credits generated by a compound, just click on a compound and the Credits will automatically be added to your account.

If your compound generated a certain amount of credits, you may not even have to click. Placing your mouse over a compound will transfer the credits to your account.

Note that placing your mouse on a compound without clicking also allows you to see how many Credits are generated by a specific compound.