You may choose either option. You may download the Dr.Web anti-virus from the
Download section
of Dr.Web www-site and then register the serial number and receive a key file. You may also first register the serial member and receive Dr.Web key file. In this case, you should unzip and save this key file into known to you location. Then you should download and install the Dr.Web anti-virus. During the installation you should omit the registration procedure. When the installation completed place the license key file to Dr.Web installation directory (in MS Windows it is usually C:\Program Files\DrWeb).