When creating shared licenses, MATLAB and each toolbox are often purchased with different numbers of permitted simultaneous users . For example you might use Statistics all of the time but a coworker might never use it and each of the two of you might need Global Optimization from time to time but not simultaneously . Perhaps on average two out of 5 of your group are using Control Systems at the same time but it flows as to which two need it .
Floating licenses can handle these situations of purchasing a limited number of licenses that are shared by a group of people . The maximum share count can be adjusted per toolbox.
Now, when this kind of arrangement is made, it is not uncommon that when a person wants to use a particular toolbox that the maximum provisioned number of users has already been met. When that happens "no licence available " can show up.
One difficulty with Floating licenses like these is that if someone uses a licence then the licence is not returned to the pool until the user exits MATLAB. So it is not uncommon for it to turn into an exercise in finding the person who is using the licence and asking them to quit MATLAB . This is seldom convenient (and they might be away ...) . And they might turn out to be actively using that toolbox and you might have to wait.
If your location does not have a rule that everyone must log off (not just lock ) at the end of the day then people will tend to leave MATLAB running holding on to licenses they have no active interest in. Tracking and getting them to logout is just a nuisance in that case. But the more often that you have to wait for someone to finish actively using MATLAB the more likely that really more licenses should be obtained for that toolbox .
Environments differ. Some places are really good at taking into account opportunity costs of time wasted not being able too work on whatever when they need to... and other places have much stricter controls on purchase budgets that have the effect of preferring to waste thousands of dollars of salary in order to keep to a purchase budget . There is no one answer .
