Files can be stored indefinitely!
When you place a file, you can choose how to store a file. You can choose endless storage, but you can choose to delete the file after the first download. This option is useful if you want to transfer a file to a specific recipient.
Confirming your words of eternal storage see a couple of files that are stored for 17 years (since the opening of the service):
In the first five years of service (from the opening until 2012), the volume of available space for your files has been increased by 6300%!
We regularly connect new fault-tolerant storage subsystem using RAID6.
If your file will never be downloaded in the first 30 days from the date of upload, it will be removed. This remedy is intended to reduce the percentage of unclaimed wrongly uploaded files. If you know exactly what the uploaded file you will need in the future, but are not sure whether it will be downloaded within 30 days, then just download the file yourself after upload.