Some versions of 4.1 shipped with a forwarder license that expired too soon. You can get a forwarder licenseby downloading and unpacking the most recent 4.1 release.
Don't try to get it from 4.2, as it does not come with (or require) a separate forwarder license.
This post contains a copy of the proper license so you don't have to download and unpack: http://splunk-base.splunk.com/answers/12167/
negative.. the splunk-forwarder.license file is exactly the same as the one as splunk.license.. that has already been done.
and is your forwarder still forwarded data or did it stopped?
Verify the forwarder is not indexing AND forwarding.
From the GUI, you would follow these steps...
This is equivalent to outputs.conf setting:
indexAndForward = false
if it doesnot index data it doesnot need license.
You just need to do the following:
a. Windows:
# copy %SPLUNK_HOME%\etc\splunk-forwarder.license %SPLUNK_HOME%\etc\splunk.license
b. Nix:
# cp $SPLUNK_HOME/etc/splunk-forwarder.license $SPLUNK_HOME/etc/splunk.license