If you have the money you can renew the domain as long as your domain registrar allows you too which is 10 years at a time but it won't make much of a difference at all in your search engine traffic.
The website searchengineland.com get's a lot of website traffic and the domain is only renewed a year at a time according to whois info.
Searchengineland.com was registered in 2006 11 years ago so it's been online for a good while.
That's what matters most in googles search. How long the the domain and website has been around not how long the domain is registered for.
I renew my domain names longer than a year at a time but I only do so because I plan to keep the domain and website around for that long and longer and I have the money to do so.
It also helps to prevent myself from losing the domain should I forget to renew it or if something happens where for example I end up in the hospital during the time of renewal and can't renew it right away.
I renew my domains longer than a year for peace of mind.