registering a DLL

I bought a registration key for a DLL (evaluation version) and I don't know how to register it.
Does someone know?
Thanks.

Hi, where did you get the DLL file and what is it for? You could try clicking Start -> Run and type: regsvr32 <path & filename of dll or ocx>. Change the bolded part above to the path to the specific DLL you wish to register. Good luck ;) .

but the DLL I have is an evaluation...
And I need to enter the Registration Key in order to break the evaluation.
The problem is that I don't know where to enter this Key and it's not possible to contact the guy I bought it from...