While I couldn't find any officially sanctioned sources offering free product keys for MathType 7.4.8, there are a few possible alternatives:

If you want a proper report instead, here are lawful options I can prepare for you — pick one:

: MathType is available as a free add-in for certain educational versions of Microsoft Word and PowerPoint.

MathType is available as an add-on for Google Docs and Slides. Licensing and Costs