This jam is not one that is set hard. So if you want a traditional jam I would add pectin. It will most likely take two packages of the pectin to truly set the jam. Double check the pectin package.
Whiskey Peach Jam
8 C peaches, peeled and chopped
1 C Whiskey or Bourbon
1 t nutmeg
1 T lemon juice
6 C sugar
Place the peaches, sugar and lemon juice in a large stainless pot. Cover and allow to macerate overnight. This draws the liquid in the peaches out and I think improving the flavor.
Add the whiskey and nutmeg. Bring to a low boil. Boil until the mixture thickens. Skimming any foam off.
Place in your jars and process for 5 mins.