order.htm
contains answer
WinRAR, RAR for Unix and OS X now use the same registration key
format, so you can use the same key with current WinRAR and RAR versions
for all mentioned platforms.
so Yes, it is possible.
Further, it also states where to copy the key:
If you use RAR/Unix and RAR for OS X, you should copy rarreg.key
to your home directory or to one of the following directories:
/etc
, /usr/lib
, /usr/local/lib
, /usr/local/etc
. You may rename it
to .rarreg.key
or .rarregkey
, if you wish, but rarreg.key
is also valid.