Zest one of the lemons. Carefully remove the yellow outer skin of the lemon with a knife.
Juice the lemons discarding seeds. If you do not have fresh lemons you can use bottled unsweetened lemon juice.
In a small saucepan bring the lemon juice and sugar to a boil over medium-high heat. Continue to simmer for 10 minutes so the syrup can thicken a bit. Mix in the zest.
Transfer the lemon syrup to a heat proof bowl. Let the mixture sit at room temperature for 20 minutes until cool. Strain out all of the zest. Store in the fridge in a clean airtight glass jar until ready to use.