Any issue to use Lync 2013 basic client for on-premise users?

hi,

         for 1500 users, i want to integrate the lync 2013 with exchange 2013 owa and outlook. need is just for IM/presence.

         Plan is to buy the standard cals and download the lync 2013 basic clients for end users. how is this plan? any issue to downaload and use the lync 2013 client as it is freely available and we dont want to spend much on licensing.

thx