Is monthly SEO worth it?

Not by default. In Lithuania I see plenty of small businesses on retainers where the only monthly output is a PDF report. That's not worth it.

Monthly SEO is worth it when the business is in a competitive niche, when there's a real content pipeline, when technical changes keep happening on the site, or when rankings are actively being defended against active competitors. For a hyper-local service site that ranks well already, a one-time setup plus occasional check-ins is often better than a recurring invoice.

Ask what your retainer is actually buying this month. If no one can tell you, cancel it.