Change this
<!-- Enter Key as provided -->
<add key="LNK-KEY"
value="xxxxxxxxxxxxxxxxxxxxxxxx" />
to
<!-- Enter Key as provided -->
<add key="LNK-KEY" value=""
/>
the key should be used when you login as @admin@
and register the software
you will see a register link click there click that link and then
paste your key over there
the place of key in web.config file is for the
powered by removal Key
Thanks