There's no limit to the amount of money you're allowed to have in one bank account as long as the money was legally acquired.
However if a bank fails and you have more than $250,000.00 in the bank and don't remove that money from that bank before it fails then the FDIC won't insure anymore money than the $250,000.00 so you could lose the rest of the money in the bank account if the bank fails.
So if you have more than $250,000.00 it's best to spread the money out to different banks just to be safe.