grammatically, this is reported speech. We usually use "Konjunktiv I" here, but if the Konjunktiv I form is the same as the indicative form, we switch to "Konjunktiv II". So
Er sagte, er ist schlau. (wrong)
Er sagte, er sei schlau. (Konjunktiv I; He said he was smart)
Sie sagten, sie haben viel Geld (could be either indicative or Konjunktiv I, so strictly speaking, it is wrong or potentially confusing, hence we use the next option)
Sie sagten, sie hätten viel Geld. (Konjunktiv II) (They said they had a lot of money)
So in your example, the tourists said that they had paid for the food. So it seems they were told to leave before finishing their meal despite having paid for it.