How I would think that it should work is the client downloads your token when you register the software. If you decide to share your license, the more people who use your token, the more likely that token will hit the 1,000 per day / 350 requests per hour limit on the twitter API. If you were to post your registration info on a sharing site you could effectively make that token useless for you and everybody else who was trying to use it.

If somebody figures out how to trick the registration to get free API tokens on the other hand, that would be really bad for the company.