The warranty period
保修期

It's the latest and quite popular among young people.
这是最新的产品，很受年轻人的欢迎。
Yes, I know and I like it very much. I will take it.
是的，我知道，我非常喜欢它，我买下了。
Sure. Here is your receipt.
好的，给您发票。

How long is this cell phone guaranteed?
这个手机的保修期是多长时间？
You can refund it in 7 days and exchange it in year.
七天内保退，一年内保换。