The error is often related to the software failing to verify its license, which can stem from several common issues like corrupted or old licensing data, missing license prerequisites, invalid subscription, activation conflict, etc.

Recommended troubleshooting steps:

1. Please check all the license prerequisites. Update all the licensing components.(e.g. all necessary licensing services are running...)
2. Make sure you are using valid license and your license subscription is up to date.
3. Rename the FlexNet folder to refresh licensing information on the computer:
   1. Browse to C:\\ProgramData\\FLEXnet (You can directly type %Programdata% on to address bar and press enter to access this folder. You will be able to find Flexnet folder.)
   2. Rename Flexnet folder to say Flexnet_old
   3. Launch DraftSight and reactivate.
4. If above steps do not help, try clean reinstallation of DraftSight as explained in this post.

Posted on behalf of @GJ