If I ever write a memoir, the chapter dedicated to living in Scotland would be titled "paying for parsley". Parsley in Spain is free as the wind; greengrocers give it away, a bundle of sprigs tucked on top of your purchases. It´s just there, always, and if it wilts in the fridge you simply throw it in the stockpot, knowing you will get some more tomorrow with your oranges and potatoes.
It´s easy to take it for granted, because it is granted. But here, of course you pay for parsley, and through the nose, at that. Throwing leaves away is annoying.
If you use it quickly it´s nice to put it in a glass with water, like a bunch of flowers. But if not, the fridge is your best bet. I used to keep it, just like that, in a plastic container, but my new favourite book has a better way: trim the leaves, save the stems for stock, and put the leaves in plastic bag or box in the fridge. They last for many days like that, and because it´s prepped, you are likely to use it more, just as you are more likely to draw if you carry a sketchbook in your bag.
It can be the main ingredient in a salad to go with marrow bones, but a few chopped leaves is all it takes to liven up many things, like home-made soup, sauteed mushrooms, roast tomatoes, baked fish, octopus salad or takeaway pizza, so bear it in mind.