It is not ownership, and it cannot be bought outright in perpetuity. That is why it is better managed as a contractual interest than as a fixed asset.
Four points.
The registrant. The registrant must be the company. It must never be recorded in the name of an employee or of a distributor. A great many ownership disputes start here: when the employee leaves, or the arrangement with the distributor ends, the company often cannot simply take the domain back.
Expiry. Keep a domain inventory recording the registrant, the registrar, the expiry date, the administrative email address, and who is responsible for renewal. Turn on auto-renewal for the core domains, and set more than one reminder. After expiry a domain passes through a renewal grace period and then a redemption period, and redemption costs far more than renewal. Once the redemption period ends, the domain is deleted and released for registration again — at which point the company is in the same position as anyone else, and can recover the name only on the strength of an earlier trademark right, through a dispute proceeding or litigation.
Transfer and closing. Transfers are subject to how long the domain has been registered and to transfer lock periods, and require a transfer authorization code; the detailed requirements differ from registrar to registrar. On an acquisition or an asset transfer, put the domains, the administrative email accounts, the registrar account credentials and the DNS configuration on the closing checklist.
Liquidation. Transfer the domains to a surviving entity before the company is deregistered. Once the management account is no longer accessible, no change of any kind can be made.
