License expired when it is still active in the system

I've had a number of users say they are getting a license expired message when I am showing an active license in the system.

When I delete the old license and give them a new license, it still does not work.

How can this be fixed?

Are they using the latest version of TurboActivate (currently 3.4.6)? Is it on a virtual machine?

When I delete the old license and give them a new license, it still does not work

What do you mean it doesn't work? What function are you calling? What's the exact error code?