You need to have atleast version 5.5 of Lightroom to be able to import the raw images of Sony A7S.
Reference article : Cameras supported by Adobe Camera Raw
Could you please confirm which version of Lightroom do you have?
I have 4.4. How can I update?
What precise version of LR are you using? Use Help / System Info and look at the top.
The A7S requires LR 5.5 or newer.
The A7S II requires LR 6.2 or newer.
Uncompressed files from Sony A7xxx cameras require LR 6.2 or maybe LR 6.3 I believe.
You would not be able to import those files in Lightroom 4.
You can either upgrade to a newer version of Lightroom or you can use free Adobe DNG Converter to convert raw files to DNG.