Think about it this way. If you have an oil change service, you need to make your customer remember to come visit you periodically. If they want to take care of their care well, they must do it. But, at the same time, you want them to keep coming to your place, and, why not, recommend your business to their acquaintances.
For that purpose, every time they come to your facility, you can give them a custom oil change sticker. In this way, they will have a constant reminder to change their oil and more people get to know your business. So, your customer base will increase. A clever way to do it.