Domain Registry Services (Buffalo, NY) is a scam; please discard their notices. They send official-looking letters (often superimposed over the US flag) stating that your domain is about to expire and that you need to renew with them at a high cost in order to keep your domain active.
Unless your domain is managed by them (VERY unlikely and you can contact support to verify who owns your domain and where it is registered), this is a scam that will at best cost you money, and at worst could lead to theft of your domain name.
If your domain is owned and managed by Integrity, then you do not need to do anything as far as renewal. We take care of everything for you.
If you own your own domain, you are responsible for paying renewal fees to the registrar you work with (such as GoDaddy, eNom, Yahoo, etc.). Even if you own your own domain, you should renew with your current domain registrar or transfer to another reputable registrar (or allow Integrity to manage your domain). Under no circumstances should you release your domain to scammers such as Domain Registry Services.
In the event an Integrity office does fall for this scam and loses their domain to Domain Registry Services, Integrity staff will be unable to retrieve or recover the domain.