Hi all,
When a file gets downloaded 100 times, it will go to a premium file approval queue. Once a month, forum admins go through the approval queue and check each file one by one, and then determine if the file deserves a premium status or not.
If the file doesn't get approved to premium status, it will still be available for download at the Library - we also try to write a short note for the file author with tips on how to improve his/her file. The unapproved file is still eligible for premium approval later on, so if we see your updated file in the approval queue again and notice that it was significantly improved, we will definitely give your file the premium status by then.
For files that are part of a series (e.g., a group of 5 "Tropical Fruits" files), the download count is still done separately for each file. Sometimes a file from a series does get downloaded more times than the other files from the same series, and that's why there are a few cases where only one or two files from the same series have the premium status.
The guidelines Bystre deti reposted still apply, although we tend to be more lenient when it comes to foreign language files (especially if there aren't that many files for that particular language).
Bystre deti, about your screenshot - those that say "0 (paid)" under Cost means those particular files are premium files that you've already downloaded before (whether you downloaded the file before or after it became a premium file). If Cost is "100" or "200" that means it's a premium file that you haven't downloaded before - the number also corresponds to the number of points you need to "pay" for that download.
Note that when downloading any premium file, you only pay the points for the first time you download it. When you redownload the same file later on, you won't pay again.
At the moment, even if you are the author of the premium file, our system will still charge you for points (if you've never downloaded that file before). We'll surely add this to our to-fix list!
Bystre deti, please PM me with a list of the old files you wanted to download and I'll see how I can get them for you.