A merchant ID is required for using <a href='https://developer.paypal.com/docs/classic/express-checkout/in-context' target='_blank'>In-Context Checkout feature</a> within this integration. You can look up your merchant ID by logging into <a href='https://www.paypal.com/' target='_blank'>https://www.paypal.com/</a>. Click the profile icon on the top right side of the page and then select <b>Profile and settings</b> in the <b>Business Profile</b> menu. (If you do not see the profile icon at the top of the page, click <b>Profile</b>, which appears in the top menu when the <b>My Account tab</b> is selected.) Click <b>My business info</b> on the left, and the <b>Merchant account ID</b> is displayed in the list of profile items on the right.