Off-the-Shelf Content: Help!

I have some questions that I am hoping someone can answer for me...or at least point me in the right direction. I've been trolling and coming up empty....It's kind of an e-Learning 101 question, but not in my realm. I've always been about custom content.

So -- how does off-the-shelf content work? Say, if you're purchasing a course library from SkillSoft or some other vendor:

• If a client has their own LMS, do they purchase the courses outright and host them on their own servers? If so, is the vendor able to track usage or do they just sell the content for a flat fee based on LMS seat size?
• Or do clients purchase courses that can be launched through their LMS, but that are hosted by the off-the-shelf vendor? So the vendor can closely track actual usage and charge based on that actual usage?
• How are off-the-shelf vendor pricing models generally structured? By actual usage? By projected use (based on some factor like LMS license)?

I'm trying to advise a client but I have little to no experience in this area.

Thanks!