No, standalone does not use a license.  The agent uses a license.

If a client is not reporting for more than 30 days and you want to delete it, run the 'Client with no configuration in N days' report for a 30 day period, then right-click the results and choose Delete.  However, I recommend you manually Retire clients to retain historical data.  Otherwise you end up comparing an inventory to Altiris and find out that 30% were deleted because of communication problems.  To do this for agents not reporting for 30 days, you would right-click and choose Set Asset Status > Retired.

Again, I recommend you have a process in place to make sure there's a reason the client is not reporting.