VirtualChemlab presets unavailable

The licence has been activated. I used for a month or so then the preset labs disappeared in Virtual Chem Lab.

This sounds like a situation where you may have antivirus software that has targeted & deactivated part of our program. What antivirus software do you have?
You will need to create exceptions/exclusions for the folders where our program is.
Please reach out to us from the support page if you need more help with that: