Okay seems like some people are still a bit confused.
Q: What happens to Harry's life, money business etc?
A: Honestly guys it just depends on the little and what they want. Some may only be little once in awhile and big the rest of the time. I'm writing Harry as more of a 24/6 little. Meaning that he will be mostly little because that's the kind of story I want to write but as the story progresses he may start to switch more often it just depends.
While a little is 'little' their money, possessions and anything else is still theirs but their guardian might look after it for them when they are mentally too young to do so, or maybe the bank. The wizarding world understands littles and their needs. Obviously little can't be an Auror or someone high up in the ministry but other jobs are fine.
Harry will not 'age up' he will stay at 2 ½, most littles do not change ages they may show characteristics of someone around the same age but not that big of an age gap.