The HiFi tier is normally $15 per month, although Deezer hopes to reel you in by offering it for free for the first 90 days if you sign up before the end of 2019. The challenge, as always, is the competition. Services like Tidal and Qobuz have their own high-quality options that may be enticing, and that's provided you're itching for higher-quality audio in the first place. If you're not about to venture beyond the earbuds that came with your phone, you probably won't get much benefit from FLAC in the first place.