Microsoft has an update, if you can call it that, to the Office Web Apps Server that is used (amongst others) by Lync 2013.
This “update” is 584MB of download, and will require the following procedure to update your Lync 2013 WAS (WAC) server(s). If you have a one server pool, no problem.
Open powershell on the host server as and administrator….
Do a Get-OfficeWebAppsFarm just to confirm the box thinks the farm is gone. Then run the update. It won’t take but about 10 minutes and wants a reboot.
Then recreate your Office Web Apps Farm with “new-OfficeWebAppsFarm”
If you have a pool of two or more servers, then you might think you can do one node at a time, right?! Not so fast young Padiwan. Remove the WebAppsFarm in its’ entirety. As in take it completely down. Go to each node in the farm, and run the Remove-OfficeWebsAppsMachine. Once the last server is out of the farm, ensure the farm is really gone. Then run the patch/update in, then reboot the entire mess. After that, recreate your Office Web Apps Farm. You did record all those commands when you first put the farm together, right?
Enjoy taking the entire farm down for an update.