Summarize:

Once you've purchased your options contracts, you're essentially playing a waiting game. Watch the stock to see if it moves in the direction you predicted it would when you bought your options. Most brokers allow you to set alerts that will send you a notification when a stock falls below a certain level. You can use these alerts to more easily manage your options. You can exercise your option at any time before the expiration date. When you buy a put option, the seller of that option is obligated to buy the stock at the strike price any time (before the expiration date) you present that option to them.  If the stock declines below your strike price, you are "in the money" if you have a put option. You can put your options to the seller and the seller will have to buy the stock at your strike price, even though it's currently trading for less. For example, suppose you have 5 contracts (representing 500 shares of stock) with a strike price of $100. The underlying stock of those contracts drops to $80. When you put those options to the seller, the seller is obligated to pay you $50,000. Since the underlying stock is only worth $40,000, you've realized a $10,000 profit. Options have both intrinsic value and time value. You may want to sell the options if the stock has declined as you predicted, but is trending back upward.  For example, suppose you have 5 contracts (representing 500 shares of stock) with a strike price of $100. The stock dropped to $80, then rebounded to $85 and is trending upward. If you sell the contracts at the strike price, you will make $7,500. When you sell an option, you then become obligated to purchase the stock at the strike price. To continue the example, suppose the stock continues to rise to $125. If obligated to buy the stock, you would make an additional profit because, after buying the stock for $100, you could turn around and sell it for $125. If your prediction didn't pan out and the stock increased in value or stayed the same, you're "out the money." Since there's no obligation to exercise an option as the buyer, you can simply let it expire. When you let an option expire, you'll be out the premiums and fees you paid for the option, but that would be all you would lose.
Keep your eye on the stock. Put the stock to the seller if the stock declines. Sell the contracts themselves if the stock declines before expiration. Let the option expire if the stock doesn't decline.