Once the node count has been reached, you will no longer be able to add any new nodes to inventory (i.e., if they already exist within inventory, machines will continue to check-in and update accordingly). Any new nodes that aren't currently inventoried will be rejected at the bootstrap process and not added into inventory. These computers will continue to try and be inventoried but will be unsuccessful until other items are removed from inventory first..
This means if all of the nodes are connected (say 100 of 100 systems on and AMP connected to the KACE SMA) additional devices over the node limit trying to check in will not be able to do so.
Some issues associated with this scenario:
Intermittent device check in depending on the connection of nodes being exceeded result in::
To free up license nodes: