I didn't see this in there but support and maintenance is a great recurring spend. For enterprise software this can be 20% of the purchase price, if you give a discount on the software (this can give the purchasing folks a win to take to their boss) you can often get the S&M at full undiscounted price. Get enough of these deals and making payroll every month gets a lot easier.
Put an extra line item in the quote for maintenance. Done.
Seriously, not only does that work, there are companies which will send the quote back and ask you to requote them with a maintenance contract if you don't do it the first time.
(And yep, 20% is indeed quite standard at many places.)
"Remember that time we bought the thing? And we had that bug? And they said 'We'll never fix that because the product is EOL'? That should never ever happen again, and is worth 20% per year to insure against."
AR quotes maintenance purely as "We promise this product will be under active development for the duration of your maintenance contract. We might decide to do that independently of this contract, but if you want a legally enforceable promise which you can quote to other stakeholders, that costs $PRICE."
To be fair, even if it never gets used, it's a hedge against the risk of relying on a third party.
My last project was heavily reliant on a particular feature in a game development framework. We were more than 1 million into development when they announced they were discontinuing the feature. We had a service contract, but not a maintenance contract. They basically told us at that time that all those bugs we had filed over the last 6 months? Here's the code, fix them yourself. We pivoted as hard as we could, but it was too late and we had spent too much money. The end result is my company canceled the project and laid off my entire studio.
