This forum it's English only, you should use email support if you want to write in italian.
The X-Class product line doesn't use an activation system, so it can be reinstalled without having to be careful about hardware activations, you only need the Serial Number and the installer.
If you lost your purchase receipt Serial Number, you can retrieve it as explained on our FAQ page:http://www.fsdreamteam.com/faq.html
However, the problem it's the installer.
Since X-Class doesn't use an activation system with a freely available download, the download link can only be accessed after you purchase it, after that it expires, unless you purchase the EDS (Esellerate Download Service), that keeps your download available for 12 months after the purchase. If you chose not to purchase that service, you have the responsibility to store your installer download safely. Since even that service works for 1 year only, you should keep a backup of the installer in any case.
I'm explaining this, because your experience clearly shows that having an online hardware activation system that allows to keep the download freely available it's much better for users. Some people mistakenly think that having an activation system will cause the "problems" when changing PCs.
Instead, what happened here, shows exactly the opposite: you are having a problem after changing a PC exactly BECAUSE the product doesn't have any activation!
If this was any other FSDT/Cloud9 product with the activation, it would have been enough to download the always available installer from our website, without having to worry about "download insurances" or having to keep your installer stored safely.
Now, if you would like to contact us via email (you CAN write in Italian, with email), I'll look into a solution for your issue. We don't want you to have repurchase the product, even if technically you should, but it was important for me having the chance to explain exactly what happened, and dyspel once again the popular myth that "activation is bad if you want to change hardware", because this episode demonstrates exactly the opposite.