As of v3.0, FLEXlm has an optional new format for license files. FLEXlm products always understand older versions; therefore, the pre-v3.0 files are understood by every FLEXlm version. However, your old applications (pre-FLEXlm v3.0) will not be able to use the new license file. See also Section 2.2, License File Format Overview, in the FLEXlm End Users Guide.