Unable to check out license Error -7

I have two Matlab code projects. One of them is used to do regression testing on the other one.

The code I use for regression testing is running in 4 different linux servers. In each server, my regression testing process initiates 2 to 3 Matlab sessions. Each Matlab session, on each server, runs up to 10 functions of the code being regression tested through the Parallel computing.

The functions I'm running make use of different toolboxes like Financial, Statistics, Database, etc but the linux account I'm using to run all this has a permanent license to all the required toolboxes.

The problem is that under this design, I'm constanly getting the error message included below. I used to run the exact same process but with a DEMO license and never faced this problem.

Is there some kind of threshold I'm reaching in terms license usage?

UPDATE: I forgot to mention that if I run the process in a single server with no more than 2 Matlab sessions, I do not get the license checkout errors.

ERROR:
Caused by: 
    Error using database 
    License checkout failed. 
    License Manager Error -7 
    This version of MATLAB requires a newer version of the license manager.  
    Update the license manager software to the latest version. 

      Troubleshoot this issue by visiting:  
      http://www.mathworks.com/support/lme/R2015b/7 

      Diagnostic Information: 
      Feature: Database_Toolbox  
      License path: /opt/x_ana_reg/.matlab/R2015b_licenses:/opt/net/msdist/msci3rd/matlab/r2015b/licenses/license.dat:/opt/net/msdist/msci3rd/matlab/r2015b/licenses/network.lic  
      Licensing error: -7,10015.

Answer 1

[Walter Roberson]

DEMO / Trial licenses are usually host based or Designated Named User -- that is, they do not use the license server.

You need to update the license server version on your license serving host. R2017a requires FlexNet 11.14.0.1; https://www.mathworks.com/support/install/license_manager_files.html

[Siusen Phang]

Thank you for your answer Walter.

I forgot to mention that if I run the process in a single server with no more than 2 Matlab sessions. I do not get the license checkout errors. That's why I'm wondering if there's some kind of threshold on the license usage.

I did notice the message about pdating the License Manager but will that help to resolve the specific problem I'm having?

[Walter Roberson]

There are situations where "using up" licenses on one license server can cause further requests to be forwarded to another server, so what you describe is at least theoretically possible.

Upgrading the flexnet software should resolve the problem.