SEO software like Ahrefs, SEMrush, and MOZ are indeed expensive. Moz charges $99 per month while SEMrush $120 per month.
The best way to make good use of pricey SEO software is to pay a monthly subscription and let them crawl your website pages and find problems. Then spend that month of subscription to fix the problems. Once you have fixed the problems, you will have an idea of how to prevent such problems from reoccurring. Then, cancel the subscription.
SEMrush and MOZ are only worth it for businesses offering SEO services or high revenue-generating websites.
Free SEO software, extensions, and plugins like Yoast or low-cost premium ones are good enough for bloggers.