Photoshop cs4 italian for an old mac (Mac Pro 2007 with OS X 10.7): How become the software and the license?

If you are looking to buy the software/license, Adobe does not sell older software so you would need to find a third party that is offering it.

If you have a license (serial number) already and just need to download the software you can download using the following links...

Adobe apps - download and installation help

Download Adobe Creative Suite 4 (CS4) products

You can also download the trial version of the software thru the page linked below and then use your current serial number to activate it.  Be sure to follow the steps outlined in the Note: Very Important Instructions section on the download pages at this site and have cookies enabled in your browser or else the download will not work properly.

CS3 and CS4: http://prodesigntools.com/download-adobe-cs4-and-cs3-free-trials-here.html