Suet will last a long time when it's frozen. The key to getting suet that's easy to digest is getting it from animals slaughtered in late spring or summer when they've been eating young grass and herbs. This suet will be wonderful, it will have the texture of butter and will melt in your mouth. Suet from animals slaughtered in fall or winter will be hard, crumbly and will end up like chewing gum; you'll have to swallow big pieces and they will not be as easy to digest. I'm admittedly not sure what the difference is caused by, probably a mixture of differing fatty acid profiles and connective tissue content, but nowadays I limit my suet purchases to late spring and summer.