It's a reminder that "Oh yeah, I enjoy Brand X, I should get some of their product". You may enjoy Coca Cola, but if nobody around you drinks a can, and you don

It's a reminder that "Oh yeah, I enjoy Brand X, I should get some of their product". You may enjoy Coca Cola, but if nobody around you drinks a can, and you don't ever see an ad, you're less likely to remain a consumer of the brand. It's also why you might continue getting ads for subscriptions you pay for. They want to remind you of the value continually provided-- it's for retention purposes.