Office 2019, rather than 2013 - but I bought this key 3 months ago for my new laptop, installed a treat, still working well.
I have tried Libre Office. Slow, clunky, no good for the sort of complex stuff I have to do e.g. writing scientific papers.
I am currently trialling a writing package (a bit more complex than a word processor) designed for writing books in, called Scrivener. I'd not use it for writing letters, but am pretty convinced now I'll be writing my next book in it. £43 for a full Windows licence is hardly painful.
G