Is there need any license or is there a free version of FTK 5.1?
The software is on a commercial license, you will have to contact sales in order to establish a demo session or obtain details related to purchasing. Access the link posted below to visit the official page of the product, then click on the Contact Sales link on the right side to get in touch with the developers. They should provide additional information about it.
Official website: http://accessdata.com/solutions/digital-forensics/forensic-toolkit-ftk