SpeedingCheetah answered my question by searching:
On the My Choice Plan.
One time data purchases expire at your bill cycle date.
I asked a while back if they still bought back unused data, the answer was no, that was an older plan, I use very little data, but when I need it, I need it. I’m not understanding why that data doesn’t transfer to the next billing cycle, or until it’s used up. I only used about 200 MB, so I lost 800 MB. So I needed data, and it’s gone. so one gig data can last me up to 5 months, but to have data when I need it, I have to spend spend another $5 each month, so by the time I use a gig, it’s going to cost me $25… That pretty much seem to be a rip off.