When your balance is about to expire, you'll find it displayed in red and with a red arrow.
#2 Transaction Report
If you click on SMS Balance and check the Transaction Report that appears, scroll down to the last purchase you made. Your credit expiry date will be shown in the description (click "View All" or "100 / page" if you cannot see it on the first screen).
#3 Reminder Email
Finally, we will send you 2 reminder emails: the first one 7 days prior to the expiry date; the second one the day before your credit is set to expire.