Purchase of domain name

I will be looking to pay for my domain name for a couple of years, how do i go about doing this. Or can't i.

When you buy it from Forumotion, you can only book it for one year.
https://help.forumotion.com/t10579-have-a-custom-domain-wwwmydomaincom

Just for one year, Or year after year

You can renew it at the end of the year for another year.

Thanks.