Hi charlie,
I have registered some domains for 5 years and i don't find any advantage in SEO point of view.

If you register your domain for more then 2 or 3 years, it will add some credit to your website. Because Google Consider domain registered for more ten 2 0r 3 years are not spammers.

I register my domain for 2 years..

I dont think it adds any value to your site or has any seo benefit in your site.

Yes I also don't think it matter's - I register my domain for 2 to 3 years.

Domains registered for longer periods will get a small boost from Google. That is because spammers will not register domain for more than 1 year. By registering for a long time you are showing that you are not a spammer. This will not be a great boost, but still there is a boost.

Domain registered for one year or 2 years have no impact on SERP.

But there is a point that renew your domain at least 2-3 months before it expires, some domains are set of autorenew but I noticed many times that once a domain is about to expire (like 10-15 days remaining) it start to loose its SERP.

Thanks

I don't see why it would matter. I register for one year and auto renew. For some reason, I think Godaddy charges more if you register for more than one year (don't recall 100%).

. . . I have no idea why.

It would be neat if there was a way to do some case studies and test this theory. I would doubt that there would be much of a boost if any.

Domain years registration and renewal definitely effects a bit on SEO. I've tested it out with a 1 yr renewal site versus a 5 yr renewal site with same niche and there's difference. The longer period of registration / renewal for your domain. The better and easier it rank. Based on same SEO strategy done.

While it does help to register your domain for longer than a year, it does not automatically qualify you for a favor with the Search Engines. More than often, you would barely see any improvement in your ranking. Longer registration length may give a small boost to your SEO efforts (and can act as a tie-breaker amongst two websites in ranking), but search engines never use this as a major criteria to rank websites.

If you want to stay ahead of the competition, I would recommend registering a domain name for a minimum of 2 years. It helps in your SEO effort (even if barely), gives you a “peace of mind” about the security of your domain, and also helps you to commit yourself on a long time project without the fear of loosing your hard work to someone else.

Yes i think it will be benefit in terms of SEO for registering a domains for more than one year .

"The difference between a domain that's six months old verses one year old is really not that big at all. As long as you've been around for at least a couple of months, you should be able make sure that you can show up in search results"

domain registration length give no benefits about SEO Point of view