Yes, the program is free, but if you are in the semiconductor business, you are not allowed to use it in office. Below you will find an extract from the License information found in the Help section. To use the softwre in your office, the developers need to be contacted first.
"This program is specifically not licensed for use by semiconductor manufacturers in the design, promotion, demonstration or sale of their products. Specific permission must be obtained from Linear Technology for the use of LTspice for these applications."
Contact option: http://www.linear.com/contact/