If you are re-installing an older version of BricsCAD, and are on the maintenance option, then your licence key will be re-generated when the latest release of BricsCAD is available. This means that even for installing a previous version of BricsCAD you will need to use the new licence key. You can find the new licence key by logging into your Bricsys account or by asking your BricsCAD supplier for the key.
Note that IRRICAD Link release compatible with the latest BricsCAD version is generally available 3-4 months later.
The IRRICAD Team