Error with eM Client calendar free version

Goodmorning everyone,

i have a problem with eM Client used as a calendar.
Everyday we marked the daily activities and For some time eM Client was used without activating it with the correct license key, so it showed an error message.
Before activating it with the free license I made a backup copy.
When I activated the license, about 50% of the tasks marked in the calendar were lost.
I restored the backup made earlier, but doing that eM Client also restores the unlicensed version, thus returning to the original problem.

Can someone help me?
Thank you