What are my obligations If I want to use a GPL-3.0 licensed JavaScript library on my site?

I don't want to modify it, and the script itself has URLs to their site in the header. They have a commercial version for sale, but I want to know when I should pay for it. Here's the GPL-3.0 license .

1. Do I need to provide a download link of the software on my site?

   Or a link to their site?

   Or just the license?

2. Do I need to offer the source of my site as GPL-3.0 also?
3. Can I use it if my site is for a for-profit business?
4. What's the tipping point for needing to purchase a commercial license?

1. Yes, sort of ... you need to provide the source in some way Check for instance "[...]as long as the source checkout process does not become burdensome or otherwise restrictive"
2. Sort of, either GPL or a GPL compatible license. From the GNU FAQ "If a library is released under the GPL (not the LGPL), does that mean that any software which uses it has to be under the GPL or a GPL-compatible license? Yes, because the software as it is actually run includes the library."
3. Yes, nothing in GPL prevents you from charging for the product/code
4. Wishing to leave the GPL license - no size limit or anything like that

However at the end of this, rread the license, the FAQ and make sure you get advice from proper legal advisors!