This is a daily validity offer according to the capital city time of your roamed country. E.g. if you are in Australia and start browsing from 01:00AM Canberra time, your daily validity will expire at 11:59PM Canberra time. Should you continue to browse after 12AM Canberra time, you will be charged RM36 x 2 = RM72.
Roaming usage is rated based on GMT (Greenwich Mean Time) without consideration of Daylight Savings Time (DST).