Unclaimed prizes are kept by the lottery jurisdiction. If a Grand Prize goes unclaimed, the money must be returned to all lotteries in proportion to their sales for the draw run. The lotteries then distribute the money, based on their own jurisdiction's laws, to other lottery games or to their jurisdiction's general fund, or otherwise as required by law.
The Mega Millions world record stood until January 2016, when Powerball took over the crown as the lottery champion of the world with a $1.568 billion jackpot. Changes to the Mega Millions game format have made it more difficult to win the Mega Millions jackpot and as a result, Mega Millions could soon award a record-breaking jackpot and regain its title as the biggest lottery in the world.
Once your lottery ticket is purchased, scanned and uploaded to your account, you own the ticket and the rights of the ticket – legally speaking what the agent has after scanning in your ticket is just a piece a paper. (This is why you should never trust a website that claims it is legitimate and does not following the insurance model but does not scan the tickets and send them to you – red flag).
Generally, Powerball players do not have to choose cash or annuity unless they win a jackpot (then they usually have 60 days to choose.) Exceptions include Florida and Missouri; the 60-day "clock" starts with the drawing, so a jackpot winner who wishes to take the cash option needs to make immediate plans to claim their prize. New Jersey and Texas require the cash/annuity choice to be made when playing; in New Jersey, an annuity ticket can be changed to cash after winning, while in Texas, the choice is binding (when the cash option was introduced in 1997, all Powerball players had to make the choice when playing. This regulation was phased out by 1999.) All Powerball prizes must be claimed within a period ranging from 90 days to a year, depending on where the ticket was bought.
Nowadays there is a plethora of websites to choose from and new companies offer online lottery ticket service every day. Due to the nature of this industry and the fact that newcomers are popping up all over, it is advisable to be diligent and check out the lottery ticket provider carefully before you decide to buy Powerball tickets online with them. This is easily done with a quick google search and an investment of 5 minutes on your part. Trust us, the five minutes is worth it to be sure that when/if you play Powerball online and win, you actually receive your jackpot winnings.