error message on shared computer access

Hello.  I sure hope someone can help us solve this problem.  We have adobe digital editions on a shared computer to which we use to access specific treatment materials in electronic format.  As of recently we have started to have problems with new staff accessing these materials on this shared computer.  We get an error message of

E_LIC_ALREADY_FULFILLED_BY_ANOTHER_USER

there have been many staff from the past that no longer work here that have logged into these materials too.  and now new staff cannot access these same materials.  what can we do?  is there a way to reset the number of authorizations?