These free night certificates are obtained either by having a Chase IHG credit card which gives you a free night certificate annually or from an IHG promotion. These are probably my favorite because you can use them at any IHG property in the world with no blackout dates as long as you find standard award availability. These certificates expire a year after they are issued.
UPDATE: Unfortunately Chase is changing the rules where you can only redeem free night certificates at properties that cost 40k points or less. This change will take affect for free night certificates issued after May 1, 2019, so if you want to use your free night certificate at any IHG property, do so before then!
To use these certificates, you must log into your account, go to the My Account page, and click the Free Night Status on the left hand side of the page. You will see your free night certificate(s) ready to use. If you don’t see this, you can always click here to get to the free night certificate page.
Click the ‘Book Free Night” link and it will take you to the reservation page where you can select the place you want to go and the day(s) you want to stay depending on the number of certificates you have. After you choose the available hotel, you can choose the room type you want. Note the cancellation date and time.
After you select your room, you will be taken to a page to enter all your contact and credit card details to reserve the room. Click the “I certify” box and confirm the reservation. You will receive an email with your reservation details.
Now say that you want to use your certificate beyond the expiration date. The website and a phone agent will let you make a reservation for your stay beyond this expiration date and there shouldn’t be any problems. However, you will not be able to make any changes after the expiration date passes or you will loose your certificate. Here is a flyertalk thread that shows other people’s experience with this as well.
This is particularly useful if your certificate expires before the end of the year and you want to use it for New Years Eve which I have found to get the best value from.