What is the name of the engine for activating coupons?

Question

Electronic commerce

Good evening friends! The question is the following..
I have been looking for an engine for activating promotional codes for a long time.
The essence is the following, as in any action "from under the cover": A person enters a code, say, from under the cover, or a package on the site and this code is activated. And in the admin panel it is simply displayed that this person has registered the code, but the person himself sees in his account that he has registered the code and can further register others ..
I tried to search: Promotions engine, Promotions script, Script promotions. For wordpress searched etc. But I found only modules of promotional codes for product discounts. I need something else, as I explained..
Guys, the question is really very important.. Tell me, how can I formulate it? How to search? I feel I just call it all wrong and I'm looking for ..