If you are in actor in advertising (Commercials), do you get paid only once?

It depends.

Most commercial producers draw actors from casting/talent agencies. Some agencies are union shops, others aren’t.

If the producer wants a big name actor celebrity for their product, a high dollar performance fee + residuals (royalties) is almost always offered. For unkown talent or non “A List” actors it’s more negotiable, and residuals may only be offered if the agency or talent is union.

The other factor regarding pay is obviously the company itself & product market share. The talent in all those amped-up Super Bowl ads made mega bucks. The anonymous girl cranking the slot machine in your local casino ad got lunch money.

I know a couple that had “won” a free dinner, in San Francisco, and at the end of the dinner, they were asked about the coffee. They both raved about it, said it was best coffee they had in a long time. Turned out to be Folgers, and they were filmed for a “candid camera” type commercial.

The ad played for a good nine months, and they got checks every month.

As @JLoon wrote, it depends.

My brother-in-law has been in numerous commercials, both visibly and voice-over. He gets paid once. He’s a union actor, but he isn’t well-known or recognizable. He’s grateful for every job and not in a position to negotiate.

I knew the voice of Visa (”... and they don’t take American Express”). I think he was in some Hollywood union. He got residuals every time his ad played. He was pissed that he had to redo one of them because the time and effort he put in for that first version was for naught.

It depends if you signed a contract with the company you are advertising for.
Spokespeople like Flo from Progressive, Shaq from Icy Hot or The General car insurance, or Terry Crews from Old Spice are recurring “characters” and thus get royalties.
However if you just got a one time gig shooting a commercial, that’s it. You get paid for your time in a single paycheck and then it’s done.