You can install Live on two of your own computers if you have registered your serial number on the Ableton registration page and you will not be using both computers at the same time.

If you want to run Live on several machines simultaneously, you can purchase each additional license for half the price of a standard full version. If you Ableton your address, your registered Live serial number, your credit card data (including expiration date and CSC code) and what you want to order, Ableton can process your order right away. Please write to customercare@ableton.com or send a fax to 0049 30 288 763 269.