This Auto Hotkey script provides a keystroke (Control+Shift+P) to paste your registration key into the donation prompt screen of MT Power Kit. You will have received an email containing this key if you've made a donation to support development at www.PowerDrumKit.com.
To use the script, copy your registration key to your clipboard, run MTPDK-Helper-paste-key-from-clipboard.exe, then switch back to Reaper's FX window and hit Control+Shift+P.
The script will automatically quit after a successful click.
I've verified that it works in Reaper. Not sure about support for other DAWs.
IMPORTANT NOTE:
Do not delete any of the files in the folder, they're all required for the script to work properly.
FYI, here's the list of files that should be present:
exit_after_task.txt
key1.txt
key2.txt
key3.txt
MTPDK-Helper-paste-key-from-clipboard.exe
reference.bmp
reference2.bmp

I don't know who wrote the script. If you do, please let me know via any of the Reaper accessibility groups. I'd like to send them an effusive note of thanks and to make sure they're being credited wherever this thing is being shared.

Hope it's useful!

Scott

(Last updated 7th Jan, 2021)