This watermelon salad is best enjoyed fresh, but if you need to store it, keep it in an airtight container in the fridge for up to one day. The watermelon releases a lot of juice, which can make the salad watery. To keep it fresh for longer, store the dressing separately and mix it in just before serving. This can help maintain the texture for about two days. Freezing is not recommended since watermelon becomes mushy when thawed. For the best taste and texture, it's best to eat the salad within a few hours of making it.