If the software opens without the error, make this change permanent: Right-click the shortcut again and select . Go to the Compatibility tab. Check the box for Run this program as an administrator . Click Apply and then OK . 2. Re-register the Key via Labcenter License Manager

: Uninstall Proteus entirely, delete any remaining "Labcentre Electronics" folders in Program Files , and reinstall from scratch.

Which you are running (e.g., 7.10, 8.9, 8.15)? What operating system your computer uses?

For Proteus 7.5 and earlier versions, the LXKProteus patch can fix license validation:

(usually found in the installation folder or Start menu). If the "Installed Keys" pane is empty, click to find your license file and select Check Compatibility Mode

: Ensure the "Installed Keys" section on the right now lists your valid professional license. Common Troubleshooting Steps Run as Administrator : Right-click the Proteus/ISIS shortcut and select Run as Administrator

: For professional or network licenses, ensure your computer's HostID (MAC address) matches the one the license was generated for.

) or link to a valid cloud license. You can typically resolve this by manually reinstalling the license key through the Labcenter License Manager. Manual License Reinstallation

Proteus requires specific registry and folder access to "read" your license status. If Windows is blocking these permissions, the "valid license" error pops up. Right-click your . Go to Properties > Compatibility . Check the box: Run this program as an administrator . Click Apply and try launching the software again. 3. Environment Variable Conflicts