So if I try to commend a player when I have 0 commendations I'll get the usual warning that I used all my allotted commendations so far.
However, if I am matched, let's say, next game with that player and I receive an extra commendation, I can't use it on the player I previously tried and failed to commend.

In other words, even 0 commendations still count as commending someone so you can't commend them later.