I think jeff of pa's description is pretty accurate, I've heard of these, but never actually seen one. Apparently they were a common thing in the early days of suburbs. I would add though that I think a big part of how the time limit scam worked was when someone showed up to redeem it, the agent would say "oh sorry, that offer has expired, but since you're here, let me show you what we have available, and all the wonderful house options we have and tell you all about it" Then tell you that since you missed out on the free offer they will work with you to get you a lot at a special price and then you pay their builder to build your house, and instead of the "transfer fee" you pay a couple hundred for a lot thinking you're getting a good deal. Same kind of cheap huckster scam that is still going on today in real estate, think of time share scams and predatory loans....
If anything it's an interesting piece of history and says a lot about the common mindset of the time it was made. I think it would be interesting to see a compilation of all of the known tokens of this type just to see how far and wide this practice was....