Of course, anything with that high an alcohol content will last for a very long time! Mine often stays around for a couple of years, the only issue is if the fruit is still in it can go cloudy, but that doesn't affect the taste or safety.
Sloe gin tastes better as the time goes on. Last Christmas I was making a venison casserole but silly me didn't read the recipe to make sure I had all the ingredients. I needed red wine but didn't have any but I had a bottle of homemade sloe gin. I put some of that in it instead and it was delicious. OP, that reminds me I have a bottle of blueberry gin hiding in my wardrobe. Might give that a go tonight.