Ah, OK...
Pages has not been a standard install on a new Mac, nor has it ever been part of an OS X system install. It has always been an extra purchase. However, because there is a variety of ways to get Pages, it could appear to be free - but, in fact, is not free software.
Again, if you had a backup with Pages installed, then using that backup to restore your system may allow you to download the Pages update for free. Otherwise, if you need Pages for some purpose, you will need to purchase it.