To claim or redeem your ad credit, go to your Payment settings on Facebook. You will find this under the Ad Center section. Next, under Tools, clock on Add payment method. Here, select your current location and currency and then hit Save. Now, navigate to the Add payment section, click on Ad credit, and press Next. Here, type in the ad credit code (16-digit alphanumeric) and press Claim. And that's how you redeem your Facebook ad credit.