Thanks for your posting! Sure, I’m happy to answer your questions below. Please note that my answers assume the TestRail Server edition. For TestRail Cloud this would work differently and you can change users every month.
What happens to the money when we already paid for the license to 100 users, and after a few months we need a license for 50 users: similar to most software companies we would issue the full license key the moment you order the license, so you cannot just return half of the license and downgrading like this isn’t possible. For next year’s renewal you can of course renew just for 50 users to receive a 50 user license key, so there’s no need to renew for 100 if you don’t have a need for it.
What should be done in the first place, if we want to change a license pack to larger team: change pack or pay for new pack: you would be able to buy an upgrade at any time. If your existing license is still valid for at least 3 months, we also provide a 70% discount of the previous license pack toward the new purchase. You can either do this online from your customer portal account or email is for a quote.
I hope this helps!