What @mschmitt wrote, but I’d also like to ask how many computers you use, and how long you typically go between major-version upgrades.
I ask because depending on your answer, a 365 subscription might be more economical.
For example, in my home, I install Office on four computers - my desktop and laptop, and my wife’s two laptops. I usually buy/renew my Microsoft 365 subscription via Costco, which currently charges $100 (not counting a $10 gift-card rebate) for a 15 month “family” subscription which is good for up to 6 users, each of which can be signed-in on up to five computers at once. So for me (two users, four computers), that’s $6.67 per month or $80 per year.
I compare this against (also using Costco pricing) an Office Home & Student perpetual license, which costs $130 and is only valid for one computer. So for my home, that would cost $520 for four computers.
Dividing one by the other means the break-even point (where a subscription costs the same as the perpetual license) is 6.5 years ($520 divided by $80).
Since Microsoft releases major updates every 2-4 years with support typically ending 4-6 years after the release date (see Wikipedia), I will always be upgrading more rapidly than that 6.5 year break-even interval. Which makes the subscription cost less over time.
Of course, if you’re only buying for one user and one computer, then that changes everything ($130 every 4-6 years, for an effective cost of $22-33 per year) making the perpetual license more cost effective than the subscription (at an average of $80 per year for the family subscription or $70 per year for a personal (single-user) subscription.
All the above is using Costco pricing as a reference, but you can easily do the same math for whatever prices you find while shopping.
And you need to recalculate this every time you go shopping to buy/renew, because prices always change. Back in the PowerPC days (Office V.x and Office 2004), Microsoft offered 3-computer perpetual licenses for the “Home & Student” edition. I would pay $300 for two of these packs (for 4-5 computers), for an effective cost of $60-75 per year. If that package was still offered today, it would be better than a subscription.