What happens when I finish what is given in my subscription? Can I continue using? To continue using, you may log in to your Changi Go app and add more Data, SMS or Talktime. What is the valid period for the Add-ons? The Add-on Data, SMS and Talktime are valid till the end of your bill cycle. Any unused add-on data will not roll over for use in the next month. Will my add-on fee be pro-rated if I subscribe to it in the middle of my bill cycle? No, there is no pro-ration of fee. You are entitled to the full value of the add-on purchased, and the add-on expires on the last day of your current bill cycle.