Finely shred the lemon peel (zest) to get about 1 tablespoon. Then, juice the lemons to get approximately 3/4 cup of juice.
Combine the lemon zest, lemon juice, and water in a bowl. Let this mixture stand for 10 minutes.
Strain the lemon mixture to remove any seeds and pulp. Measure out 2 cups of the strained juice.
In a large saucepan, combine the 2 cups of lemon juice and sugar. Bring to a boil over medium-high heat, stirring constantly.
Once the mixture reaches a full rolling boil (one that can’t be stirred down), quickly stir in the liquid pectin. Bring back to a full rolling boil and boil for exactly 1 minute, stirring continuously.
Remove the pan from heat and skim off any foam. Carefully ladle the hot jelly into sterilized jars, leaving about 1/2 inch of headspace at the top. Wipe the rims of the jars, apply lids, and screw on the bands tightly.
For longer-term storage, process the jars in a boiling water bath for 5 minutes. If not processing, let the jars cool completely and store them in the refrigerator.