The thinking on that is that children without severe asthma or allergic triggers may outgrow it as the lungs continue to grow and any airway ristrictions may lessen as a result. However, it can crop up again in later adult years. There does not seem to be anyway to determine if it will. I'd just avoid any potential allergens, stay healthy and not worry about it.
I was told that I had asthma as a child, but as far as I remember I never took any medications for it. Ladedadeda, I am living my life fine as can be. Perhaps I self limited some of my activity because I ended up playing goalie in soccer and First base in softball?
But last year, at the age of 47 I got pneumonia out of the blue and was hospitalized for 10 days. My pulmonologist said it was the worst case he saw that year and he suspects that it was because I had sub-clinical asthma. I am now on Dulera.
About 50% of people who outgrow childhood asthma will have symptoms again at some point. But, like Titchou said, there's no reason to worry, because there's not much you can do about it other than generally try to stay healthy.
If you have allergies, minimize your exposure to your allergens. If allergies get bad, consider allergy shots. Don't smoke, don't hang around people who do. Get flu shots. Basic things that make sense anyway. And if you do get breathing problems again, just go to a doctor and deal with it.