It changes the meaning: with de you're stating a general fact, that you enjoy drinking lemonade (as opposed to not liking it / never drinking it).
With da (you'd use a the in English: I like the lemonade) it means you're talking about one specific lemonade (presumably it's around you somewhere, you just had it, someone offered it to you, etc etc - it's clear that everyone in the conversation knows the lemonade). If you say da limonada without it being clear in context which lemonade you're referring to, people will instantly ask "What lemonade?".
Does that make sense? C:
When you like, you like "of" something in Portuguese. It means exactly the same thing in Portuguese as in English, you know? Just in Portuguese you'll need the preposition "de", because when you like someone, you GOSTA DE alguém. You don't GOSTA alguém. You GOSTA DE alguém. If it makes any sense, but it's something like this. I tried.