To download .slf file follow the steps:

1. Visit licensing.symantec.com.

2. Enter username and password.

3. Click on "New and Renewal Purchase".

4. Enter the serial number and click submit.

5. Click on Next.

6. Click on Complete registration.

7. Enter the required fields.

8. Click on Complete registration.

9. From the Licence Key tab download the slf file (eg: 21566786.slf).

10. Save it on appropriate location.

To activate the product from SEPM.

1. Open SEPM.

2. Select Admin tab.

3. Under task select "Activate Licence".

4. Select "I have a Symantec Licence File".

5. Click on Add file.

6. Select the .slf file (from the appropriate saved location).

7. Click on Next.

8. Again click on Next.

9. Click On Finish.

Your licence will be activated successfully.