The offers will show up when you visit their homepage and then click on buy premium, then a window will pop up with a special offer: one year for 39$. But this was two months ago, when I last visited their side. I don't know if the offer still exist..
According to their Fair Use Policy each premium account still only has 5TB. That was back in 2015, but they have not changed it.
"While the amount of storage space for Premium users is unlimited, if storage exceeds 5TB then files will automatically be removed as required in the following order until the amount of storage is less than 5TB: Files which have never been downloaded which were uploaded more than 90 days ago. Files which have never been downloaded which were uploaded more than 60 days ago. Files which have not been downloaded in the past 60 days and were uploaded more than 30 days ago beginning with the oldest last downloaded date. Files which have not been downloaded in the past 30 days and were uploaded more than 30 days ago beginning with the oldest last downloaded date.
A lifetime account is 199 USD which is pretty good value. A quick calculation what that means having 5 accounts ......! One of stonesvault accounts allready is lifetime and are reconsidering the number accounts we need.
If Stonesvault wants to keep all uploaded files available we must stay under 5TB per account.
I purchased the $39.00 deal last year. Well worth it. I didn't know I had 5TB of storage??
I was happy to download from FF and share on WT. If I can get the same deal at expiry I'll renew my account. I'll see about what I can do to host files there.