Hi, chendrum. The license is only for 1 computer. If you use it on several computers, your key code will be suspended. However, you are allowed to activate the program on your desktop and Laptop PC, but not running simultaneously. As for the HD space. The size of the video recorded depends on its format and the resolution you choose. Usually, if you choose the format of WMV and the resolution of 1280*720, then a 3-hour recording might take space up to 2 GB. That’s just a rough number, so you’d better prepare more space than that.