If you're unsure, you need to research. One search in Google for "nyan cat copyrighted" brings up this question and answer, and this one and this one and so on. This is the process for any resource you find online, research it before using it.
You can also search the government's database for copyright in the US and find Nyancat there.
To answer you specifically about this meme. Yes it has copyright on everything about it. There's some question about whether the owners of the copyright would pursue you for using it, so that's up to you.