The Xojo licensing is quite easy compared to other tools. You start with downloading and installing Xojo and develop your apps without a license. Later when you need to build something, you can order the license you need: Desktop, Web, iOS or Pro.
If you work in a team, you certainly want to use the some kind of version control, so you need the Xojo text based project format. This requires a valid license of Xojo, so with a company you buy your license keys earlier for that feature. And this feature makes sure you buy a license for every developer.
For the team one can have a team account and add the other accounts for your employees. Than you can buy licenses for everyone and assign them. This way all the license payments go through one person (Accountant or CEO of company) and individual developers don't notice changes. The IDE will automatically find the new key when updating the next time.
On the other side a typical school installation can go without a license. Or maybe just one for one computer which does all the builds. That makes Xojo an excellent tool for learning programming.
A new license currently is $699 for Pro. The others are cheaper, but on the long run most professional developers get the Pro as they use several targets. And with Pro you get the benefit of joining the beta program, so you can test newer version before release. At least you should open your projects in a beta and try if things still work. Would be bad if a new release breaks your project only because you did not report a problem in beta cycle.
Purchasing Xojo usually goes through their website. In the past Xojo was/is also available through various resellers or local distributors. And they participated in some bundle offers in the past.
From time to time Xojo does sales like on programmers day (256th day of the year) or Black Friday. You can find old announcements for those sales and try to predict future sales. With a typical discount of 20 or 30%, you can just buy a new license if your existing one expires within 2 months and you still save money.
You can have your license auto renew. We normally turn this off and see what we do when we come closer to the renewal day. If there is a sale for updates, you can add a year or two to your license plan. Or if your license expires, you can skip a few months and continue with old license before you buy a new license. You save more than the 10% for auto renew if you skip 2 month before buying a new license. Clever planning can save money!
I also keep an eye here for licensing and post regular about sales. If you look for a discount, feel free to email me, so I can remind you when something is available. For conferences or local meetings we had in the past discount coupons to raffle away.
PS: And if you like to support Xojo Inc. even more, you can of course just buy a second license. My account has currently 3 licenses listed. Or you join XDC to meet Xojo Inc. employers in person.