Prepaid Capped Internet Tariff

Good day

I would like to find out if it is possible to create a Tariff that has a 30gig cap but does not expire of reset after a month
I have some clients that only use the service when tay come here on holiday. I want to create a prepaid package for these clients as a once off payment. After the data has been used up they have to purchase again. This package must not expire or reset after a month