All pure honey will eventually crystallize due to the natural sugars in it. Raw honey has the tendency to granulate faster than highly processed honey as the sugar molecules have more to attach to because of the pollens, propolis and other inherent ingredients still present.
Honey does not have a shelf life. In fact, it has been found in the pyramids and though crystallized, it was still eatable; not bad for a food substance over 2500 years old. Store it on your shelf with the lid tightly sealed between 64 and 75 degrees and it will last indefinitely.
If it does granulate, loosen the lid and place the jar in a sauce pan of tepid water until it liquefies. Do not over heat it! The water should be kept below 110 degrees.
Or if you have a hot plate set it on low and place your jar on it. This is the way we prefer to do it. We have left it in the vehicle on a bright sunny day and that works as well, you could even try setting it in the window...
If you over heat it, you kill it!