Many people rationalize using a credit card based on reward points. That’s no mistake, as companies can lure tempting points, prizes and packages as incentives for using their card.

You may get the hard sell at your bank, where they offer “bonus” points or miles for singing up, and you’ve likely received some mail with these offers.

In some cases, access to these rewards comes with a price. You may pay an annual fee for access to a card with “better” rewards, or even a higher interest. At the very minimum, you may be paying interest on purchases made to earn these points.

So these points often aren’t free. Therefore, it’s in your best interest to take full advantage of the points you’ve earned.

But beware: As the New York Times points out today, these points don’t last forever. Not only do some points expire, but you could even lose points based on your payment history.

Here’s a quick guide to keeping your points, and maximizing their value:

How you lose points:

• Points expire: Most points will be with you for several years, but if you’ve been with one rewards credit card for a while it’s a good idea to check their status, which you should be able to do through your bank. But if your points or miles do hit their expiration date they will disappear.
• Points are taken away: While they may not tell you this when you sign up, your points could be taken away from you if you are late on payments or stop using a card. For example, the New York Times says American Express charges an extra fee to reinstate points if you’ve been inactive for a long period of time. And, Bank of America may block you from using points if you’re more than 60 days late on a payment.

What to do with extra points:

If, for whatever reason you can’t use your points, you can still find some value before they expire.

• Give them to friends and family. Most types of points and miles are transferable, although there may be a small fee attached.
• Donate to your favorite charity. Most card companies will let you donate miles to a charity. The miles may be turned into a cash donation. In other cases, such as with the Make-A-Wish Foundation, may even use them to make purchases.
• Trade them for points you will use. If you have different types of miles and points, and want to consolidate them you could look to online auction houses. There are several Web sites that specialize in allowing people to trade, swap and sell their miles for points they’d be more likely to use.

There’s no right answer to how you should deal with your miles as long as you make sure that you use them. After all, you’re paying for them, and there’s no reason to go deep in credit card debt to earn a few miles you won’t use.