Why does eDrawings Viewer has to be re-registered after 30-60 days?

Dear Team,

We use the eDrawings Viewer on some PCs, but after 30-60 days, it has to be re-registered, otherwise we can not use the software. There is no error message, just drops up the registration window at program start.

Do you know what can cause this, please? Or is it normal working method?

Thank you very much in advance.

Best Regards,

Renata

SolidworksGeneral