KeyThief.py

# praw is a wrapper for the Reddit API.  Makes things simple.
# re is a regular expression library.
# os is a library to interface with your OS.
import praw, re, os

# Initialize a reddit instance with the useragent user_agent
r = praw.Reddit(user_agent='fjdlsjafkldjslkfjdsklfajkdslafds')

# Get a submission stream.  This is a pretty fancy object.  Replace 'pcmasterrace' with whatever sub.  Concatenate multiple subs with a plus: pcmasterrace+gamedeals
stream = praw.helpers.submission_stream(r, 'pcmasterrace', limit=5, verbosity=-1)

# Loop through the stream.  This only runs when a new submission has happened since the last time it checked ( usually about 2 seconds )
for submission in stream:

    # Print the name of the author who made the post.  Not required.
    print(submission.author)

    # Find all things that look like Steam keys.
    m = re.findall('[a-zA-Z0-9]{4,6}\-[a-zA-Z0-9]{4,6}\-[a-zA-Z0-9]{4,6}', submission.selftext)

    # Print out the matches.  Again, not required.
    print m

    # If m is not an empty object then we have something that looks like a key.
    if not m == []:

        # Limit to only one author to prevent being a jackass.
        if str(submission.author) == 'eegras':

            # Output it got a match.
            print "Got a match"

            # open keys.txt, create it if it doesn't exist and truncate it to 0 length
            f = open('keys.txt','w+')

            # write the key to it.
            f.write(m[0])

            # close the file to actually do the write.
            f.close()

            # Run the autohotkey script.
            os.system("getkey.ahk")

            # Delete the text file.
            os.remove('keys.txt')