If you need to free up some DocRead licences, because you have users that no longer work in your organization, then follow the steps outlined here.

Before we explain how to free up licenses, it's important to understand how DocRead processes new tasks : 

How DocRead Task Processing Works.

When you configure a document to be sent to a "Required Audience" with DocRead this will be done in a batch, so the following process will occur ...

A. DocRead will count the number of users in the Group(s) that need be given Reading Tasks for that document.
B. DocRead will also count the number NEW users that currently have no Assigned, Completed or Overdue Tasks for ANY document.
C. Finally, DocRead will test to see if the number of new user licenses will exceed the permissable license allocation. If it does then NONE of the tasks will be created for that group.

As an example, imagine this scenario:

CURRENT NUMBER OF USER LICENSES : 495
TOTAL LICENSE COUNT ALLOWED : 500
NUMBER OF LICENESES REMAINING : 5

- A DocRead Publishers assigns the "Health and Safety Policy" to "Finance Group". 
- The Finance Group contains 10 users; 4 of which already take up 1 license each and 6 are NEW and will need a new license.

When DocRead attempts to process the "Health and Safety Policy" it calculates that there are 5 (500 - 495) available licenses remaining, but it needs 6 (10 - 4) to proceed. This results in a license shortfall of 1 license, which causes none of the Reading Tasks for that document to be created.

As a final point, if you remove all of a users Tasks, but that user is still in a group assigned to a document, then DocRead will create a new Reading Task causing the user to take up 1 more license again.

Step 1 : Temporarily disable the timer jobs in Central Administration.

Go to : Monitoring > Timer Job Definitions                

Find the 4 jobs starting with DocRead and click on each one. When you see the disable button, click it. This means all 4 jobs are now disabled and will not run.

 Step 2 : Remove existing tasks for users.

In this step, you will need to locate any reading tasks that have been allocated to those users in your farm. To do this, visit all of the sites where you have previously assigned tasks to the users with DocRead. Locate the ‘site tasks’ menu available from ‘Site Settings’. Once in there you need to highlight the task in the list and click on the trash can (located at the bottom) of the list. On the pop-up select ‘Selected Task only’ and click ‘ok’. Repeat this for all tasks for that user, until the user no longer has any outstanding tasks.

Step 3 : Remove the user from SharePoint Group and / or Audience.

If you are using a SharePoint group (to assign the document with DocRead) you will need to ensure the user is no longer a member. To achieve this, simply locate the group in SharePoint and select the user and choose ‘Remove User from Group’ as below.

Step 4 : Re-enable the timer jobs (IMPORTANT)

You need to re-enable the jobs that were disable in step 1 - failure to do this will result in no tasks being processed.

At this stage you will need to wait until the audiences synchronisation job as run once, followed by the Readership Processing job. These two jobs will cause the user to be removed from DocRead and then allows you to re-allocate the license to another user.

 You can check the number of available licenses by looking at the licensing screen in Central admin as follows. The 'Remaining Users' count should have increased by this stage. 

Please note : Even though all the tasks have been removed – receipts are left in place so that you have still have an auditable history.