It’s bit of both. 七輪 can mean seven rings, but more often it refers to the grill. Just as 五輪 can mean 5 rings, but it also means the olympics.

Assuming that the Norwegian system is in anyway similar to the Finnish system I use, they just print the system id and the n:th of you on a piece of receipt while the system just checks that no similar register/customer id’s have passed.

We tested this with friends where multiple friends bought stuff from the same register, but exited using only a single one and they were usable afterwards, but only once per.