Melt butter in a heavy saucepan over medium heat; add sugar and lemon juice, and cook, stirring constantly, 6 to 8 minutes or until mixture turns a deep caramel color. Gradually add cream, and cook, stirring constantly, 1 to 2 minutes or until smooth. Remove from heat, and cool. Pour into hot sterilized jars, and seal. Store in refrigerator up to 1 month.