Lemon trees are the easiest trees to keep alive, unless there's a world-class assassin hell-bent on killing it. In that case, stay inside and wait for it all to be over. Sorry for that hyper-specific piece of advice, but you'll be happy you had it if that situation ever happens to you. My main point is to tell you to invest in a lemon tree. It's the gift that keeps giving. You can make lemonade whenever you want, you little entrepreneur.
This invention will go hand-in-hand with your lemon tree, or your anything tree for that matter. I'd love to test the limits of its power. Take, for example, a jelly donut. Could I spritz jelly out of the donut? How about a juicy chicken breast? I could give any piece of food the essence of chicken. What a world!