Yes store bought gravy can be frozen in freezer safe containers.
If you have canned gravy it will last for 5 to 10 years without being opened on the shelf.
But once you open the can gravy it should be refrigerated or frozen and placed in a freezer safe container if you're gonna freeze it.
The gravy will last for 4 to 5 days in the refrigerator and up to a year or sometimes longer in the freezer.
After 6 months though the gravy will not be as fresh but still safe to eat.
You can freeze any type of gravy including the store bought and homemade gravies that you have leftover and then thaw it out when ready.