Is last years mincemeat ok to use?

Hello. Last year I made delias homemade mincemeat. It has been stored in a sterilised jar, I still have lots left. I am unsure as to whether I can still use this. Delia says it keeps for 3 years I have kept it in a dark cupboard but of course with the hot summer it hasn't always been cool. It has beef suet in it please advise before I took all the mincemeat away and make more regards