If you own a business and you advertise, the card you should be using to pay the advertising charges is the American Express Business Gold Card.
You will earn extra Membership Rewards points if you use this card to pay for advertising.
As of November 2018, you can choose two of the six categories to earn 4x Membership Rewards points per $1. These categories are…
Airfare purchased directly from airlines
Advertising (online, TV, radio)
You earn 1x Membership Rewards points in the remaining four categories and on all other purchases.
4X points applies to the first $150,000 in combined purchases from these 2 categories each calendar year then earn 1 point per dollar.