I've created about 10,800 PC Stitch .PAT files so far. These would easily fit on a 32 GigaByte (GB) USB Flash Drive. If you've got that many or more I'd suggest making sure to use USB 3/3.1 to cut the wait time for the transfer of files. I believe you don't need a code if you're using the CD-ROM version of the software.
They would take far less space if zipped! PCStitch files compress fairly well. Zipping has the added advantage of taking out the "buffering" between files (extra space required for the formatted minimum block size".
For those not that techy - what that means is: If you have a file that only needs 50 bytes but the formatted minimum block size is 1 K, then there are 974 bytes stuck at the end of the file that are not needed. The purpose is to make file allocation more efficient. If you zip files, not only are extra stuff from within those 50 byes removed, the extra 974 bytes is removed by ramming it next to the next file in the zip.
Some files don't zip well (such as .exe files) and there may be other reasons to zip them.