I've purchased and been using AxMath for a long time now - but suddenly it says "UNREGISTERED" - but I can't locate my KEY

[Dr-Bones2]

I've purchased and been using AxMath for a long time now - but suddenly it says "UNREGISTERED" - but I can't locate my KEY
I've searched my emails and found the order email - but no-where is the LICENCE KEY
So can you tell me how you delivered it (email?) and what I can search for to locate it?
I haven't changed or upgraded my computer recently - so this is baffling...
...I have tried emailing directly

[loongmxbt]

Hi, please use this key: M2W3W-2R8XY-JX8KD-2X4SL-RV8Z8

[Dr-Bones2]

Thank you - It works now. I benefit hugely from this software - is there anywhere you'd like me to review it?