You do not need to register the unit to update.  To update go here:  http://www.auteltech.com/TPMS Diagnostic & Service Tool/351.jhtml
To update Read page 30 and 31 of the updated user manual.
There  are  two separate items  to  be  updated,  the  program  and DTC,  which  should  be  updated  at  the  same  time. 
To  update program,  click the  upper Select  File button  and locate file ts401.bin from the files you recently downloaded, and then click the upper Update button. To  update  DTC, click the  bottom Select  File button  and locate file ts401.aut, and then  click the bottom Update button. Once both updates are complete, the tool is updated and ready to go.
NOTE:  If  the  updates  are  not  synchronized, the  tool  will prompt a message “Aut  version  is  different  with  bin  version!