Renewal is separate from acquisition
An aftermarket purchase transfers the domain asset; it does not eliminate future registrar renewal charges. Some extensions may also have premium renewal structures, so check the exact domain before buying.
Operating costs are business costs
Website hosting, email, DNS services, security tools, and optional privacy products are separate from domain ownership. They may be inexpensive individually but still belong in the total budget.
Avoid accidental loss
Enable renewal reminders or auto-renew where appropriate, maintain a current payment method, and keep registrar account recovery information secure. The cost of losing a critical domain can dwarf the renewal fee.