If you've downloaded the Recuva "Installer" and run it, it will install the program to it's default location (C:\Program Files) no matter where you run it from.
What you need is the Recuva "Portable" version available to download here ...
This isn't a Pro version but there isn't any difference in the scanning abilities of Pro or Free versions. The difference is in the direct priority support and some features.
However, because you have purchased a Pro licence you will still be able to contact Piriform Support direct to answer any problems you may encounter using the portable version. Or to request advice.