Social Spy is based on a 'per-computer' licensing system. You must purchase one license to monitor one computer.
Social Spy's latest pricing schedules can be viewed here.
System Requirements Processor: 500mhz minimum OS: Windows NT/200x/XP/Vista/7 (32 or 64-bit) Memory: 128MB RAM minimum Hard Disk: 2MB disk space minimum Internet Connection: Broadband recommended