Makes four cups of jam, enough to fill five 8oz containers with room to expand.
In a large bowl, crush your peaches with a potato masher. Mash them until they're a consistency you like.
Add in sugar and lemon juice, stirring until well mixed. Let stand for 10 minutes.
Gradually stir in the pectin, making sure that there are no lumps. Keep stirring for another 2 or 3 minutes to make sure the pectin is completely dissolved.
Ladle jam into clean jars or freezer-proof plastic containers, making sure you leave about half an inch of headspace so that it can expand.
Let sit for at least 60 minutes before storing so that it can fully gel. Store in freezer for up to one year, or in the fridge for three weeks. Remember that this is not heat-treated jam, so you can't store it at room temperature.