Find users with permission set licenses

Please follow the steps mentioned below :

• Go to the Developer Console

• Click the Query Editor tab towards the bottom left 
• Copy and paste the following query in the Developer Console: "SELECT Name, Id FROM User WHERE Id IN (SELECT AssigneeId FROM PermissionSetLicenseAssign WHERE PermissionSetLicense.MasterLabel ='NAME OF THE PERMISSION SET LICENSE') AND IsActive=true ORDER BY Name"  Note: Make sure to change the phrase 'NAME OF THE PERMISSION SET LICENSE' value to the actual permission set name (i.e. Sales User) before executing the command in the Developer Console.
• Click Execute.

This will display a list of every ACTIVE user along with their internal Id, who have that license. If you would want to view the assigned license(s) of INACTIVE users, you would need to replace the "IsActive=true" with "IsActive=false"

Note: If you are not sure about the name of the licenses, please get the name from under permission set license assigned from company information. 

The steps on this article are only applicable and will only work for Organization that has API access. For more information see Salesforce Editions with API access

PermissionSetLicenseAssign is the junction object that links a user to a Permission Set License