What do you do when you have ServletExec that was installed by someone before you and it logs the following message?
"ServletExec Max Concurrent Requests Exceeded, When not registered, ServletExec supports a maximum of 3 concurrent requests."
NewAtlanta ServletExec 6.0.x is bundled with Single Sign-On Policy Servers upto R12.52SPx.
The error means you have not entered the license key.
Without the license key it will run in demo mode so it is likely that you will encounter this message.
Back to the question, what do you do now?
You don't have the password for admin account or maybe to make it worse the /servletexec/admin is not accessible.
If you navigate to "<ServletExecAS>/se-<instancename>/ServletExecData" folder you will find "servletexec.xml" file.
It has the following content.
Backup the file first.
Enter the license key(which is also bundled together with the servletexec binary if you extract the Single Sign-On zip file) at the <serial>******</serial>, save and restart the ServletExec.
Check if the error goes away.