On occasions, the licence updater stays in memory and doesn't end properly if ran from a scheduled task (you can see it running in the Task Manager as HelmLicence.exe).
This then causes you to not be able to login to Helm.
The problem is actually to do with Internet Explorer settings. Take a look at the Windows scheduled task that runs the licence updater. This can be found here: Start > Programs > Accessories > System Tools > Scheduled Tasks and is called Helm Licence Updater.
Right click it, choose "Properties" and make a note of the user that is set to run this. It is usually HELM_ADMIN, and the password is the password you chose when installing Helm.
Important Note: If you changed the servername AFTER installing the control panel, you will need to alter it here. For instance if your server was called MYSERVER then the licence task would have been running under MYSERVER\\HELM_ADMIN. If you changed the servername to NEWSERVER then you need to make sure that the task also changed, so it is NEWSERVER\\HELM_ADMIN.
You can either keep this the same, or change it to Administrator or some other user you know the password of. Next, login to the server as that user. So if the task was running under HELM_ADMIN, you need to login to the server as the HELM_ADMIN user. The password for this will be
a) either known to you if you are running multiple servers because you will have needed to create this user on all of your remote servers or
b) if you are running a single server, it's the password you chose when installing Helm. If you forgot it, you can reset it in the System Identity tab of the Helm Configuration Tool (make sure that if you do this, you reset it on ALL remote servers that you have too!).
Now run the scheduled licence updater task (go to the task, right-click it and choose "Run"). You should find you get a internet explorer pop up box - click OK and tick don't show this again. (if you have changed it to another user, you may not see this box as you may have already logged in some time ago and this pop up was clicked on before).
Now you can log out and back in as the normal user you log in as. You can now see the problem - when the scheduled task ran as that user, the Internet Explorer pop up box was waiting for a confirmation click - however you never saw it and that task was held in memory. It must have been in memory and never ran again for more than 30 days - if it doesn't run for 30 days, you get that license error.
In the rare event that this doesn't solve your problem - check the system date of the server. It should be today's date. If it is set in the past or the future, it may cause issues with the licensing. Set it to today's date, then try and log in. If neither of these suggestions work, contact Odin Support and provide the license key in question.