Good questions, @Babakness. Your questions aren't annoying at all; in fact, we love folks like you who show so much respect for the licensing terms and aim to honor the work of other developers. You're exactly the type of customer we love to serve.
I completely understand your caution too; if costs aren't clear up front, it makes it very difficult to gauge if GSAP's awesomeness is worth building on.
Don't worry; we try very hard to be more than fair and always air on the side of generosity with our customers. In 18 years of being in business, we've never sued anyone and our business model is almost entirely based on the honor system. Hopefully our track record proves that GreenSock isn't a scary company to get involved with. Trust is a BIG deal to us.
The "Simply Green" and "Shockingly Green" memberships include various bonus plugins but are intended for individuals, thus only the standard license applies. The "Business Green" memberships get the expanded coverage of a commercial license (and all the bonus plugins of course).
2 & 4: Your license covers an unlimited number of your Work Products while it’s active. The only other caveat is that it covers your unedited work, meaning that if your clients/customers want to make any changes, they’d need to get their own license. Otherwise, it’d make it easy for a huge company like Microsoft to circumvent the license by hiring a freelancer to start a project and then take it in-house and piggy-back on that single-developer license without getting their own license for their numerous developers. See what I mean? But again, all of the work you do is covered as long as it’s not edited by others outside your organization.
If, for example, Company A develops a Work Product that uses TweenMax and sells it to Company B who will be licensing it to end users, Company A should have a “Business Green” membership. Company B would not be required to have a membership. If, however, Company B prefers to maintain a membership instead, that is perfectly acceptable as long as it wouldn’t reduce the club level, meaning if the development company has 20 developers and Company B has 1 developer, it wouldn’t be fair to circumvent the terms by only having Company B get a single developer membership. A 20-developer membership would be required. Again, only one of the companies needs to have the license, not both.
3: The ads themselves don't require any special license, no. If the site that's displaying them uses GSAP and it is indeed charging multiple users a fee (in this case, the advertisers) for something related to that product (the site in this case), then yes, technically it'd be appropriate to get the proper "Business Green" license.
5: Only if they update GreenSock-related code. In other words, if the "fresh out of college" developers never touch a line of GSAP code, there's no need for that company to get their own license. The original developer's license would cover it.
6: Wow, that's a big company! We'd love to have them as a customer (ha ha). You only have to count the number of developers who may interact with GreenSock tools. So in your example, that's only 1 developer, not 50,000.
So in summary:
You only need to count the number of developers who'd interact with GreenSock tools.
Your license covers all of your unedited work, even if your clients are reselling it. If your customer wants to make edits themselves, they should get their own license.
Our licensing is based on the honor system; we've never sued anyone. No need to be scared that GSAP has a bunch of thorny tentacles that'll invade your work and make things really awkward and expensive.
Hopefully our licensing model actually boost your confidence in building on GSAP because it's what has allowed us to continue to innovate and support our products, unlike most other libraries that fade after a matter of months. GSAP is very unique in this regard.
Does that help? Don't hesitate to ask if you've got any other questions.