Page "Software licensing audit" Paragraph 4

If the auditing company self-dependently scans the code base, one of the serious challenges is the license changes between versions.

Some software libraries start with one license and later switch into another.

The typical examples are switching from the single permissive license to the dual licensing model ( the choice between strong reciprocal or paid commercial ) as for iText, switching from more reciprocal to more permissive license ( as for Qt Extended ) and opensourcing the previously commercial code ( as for OpenJDK ).

In such cases it is not enough to detect that some library or code fragment has been used-an exact used version must be correctly identified.

Further difficulties may arise if the library owner removes the obsolete versions ( that were under different license ) from the public sources.