Additionally, it’s just a limit on how much you can download. You can still get 10 subtitles a day for free.
Your consumer can query the API on its own, and download 5 subtitles per IP’s per 24 hours, but a user must be authenticated to download more. Users will then be able to download as many subtitles as their ranks allows, from 10 as simple signed up user, to 1000 for VIP user.
OpenSubtitles.org is shutting down it's previous API. Now only authenticated access allowed. (blog.opensubtitles.com)