Can turbotax be installed on multiple computers?

The CD/Download products can be installed on multiple computers (there is an activation code, which is good for up to five installs) and you have a license for your own personal use.

You cannot sell your copy of TurboTax after you have installed it.

See the End User License Agreement
https://turbotax.intuit.com/corp/license/desktop.jsp

See Section B 1 C
C. Additional Restrictions. In addition to the restrictions in the Section A Terms:
You are not licensed or permitted under this EULA to do any of the following: (i) allow any other person to use the Software; (ii) rent, loan, resell, share, distribute or redistribute the original CD or a copy of the Software to any other person or entity; (iii) make the Software available on any file-sharing or application hosting service; (iv) electronically send the Software to any other person or company; (v) copy the printed materials or user documentation accompanying the Software other than as necessary to support the uses permitted above; (vi) use the Software for any commercial purpose (i.e., tax return preparation for a fee or other consideration); or (vii) use the Software to electronically file more than five federal returns. Any person or company who received the Software through any of the foregoing prohibited methods, or through any method other than purchasing a license for this Software from Intuit or an Intuit authorized retailer, is not authorized to use such Software.