There are ways to remove the Stencyl logo in Flash without paying, but only a super jerk would steal from a small, honest startup company.
A more extreme example of the honor system would be, back when Mac OS X was sold on disks, it had absolutely no DRM or license keys at all and you could install a single copy on as many computers as you wanted, but they still sold 5-user family packs, which as far as I know contained the same single disk as the single user pack, save for a sticker that said "family pack."