This is really strange. Due to some reason the license key could not be read or there is a temporarily network routing that you make. The license key is checked before initialization of all modules by CmsHttpModule.
1 - Could it be because of the contention over reading the license file? My opinion, is "Not likely".
So far, the trial message has happened only when restarting the clients.
You could try to put the key in App_Data folder and set licenseFile property in <cms> node of the web.config to ~/App_Data/LicenseFile.xml
2 - How often is the trial message supposed to come up, usually? It comes up very rarely.
Should we have another look at the license key. Maybe it got generated wrongly?
The trial message appears randomly within 50 requests. I suggest that you should check your license keys through Sitefinity >> Account section.
3 - If a page has been developed under a trial version of Sitefinity and then stored in the
database. Then the page is accessed under a fully licensed version of sitefinity, could
that be the problem?
This could not be the issue and there is no relation between the objects create under trial mode and licensed mode.
If the problem persist you can contact our sales department to verify the keys you have.
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