Dear Villival,
pls convert your Registration date as per as your Current date with the given formula and than substract your current date with registation date
here is the attached file for your better understand
=DATE(MID(A2,FIND("/",A2,FIND("/",A2)+1)+1,4),MID(A2,FIND("/",A2)+1,2),LEFT(A2,2))
regards
Naresh