How to record income for multi year opportunities

We are selling Software-as-a-Service for mostly 1 year contracts, but some clients have multi year agreements, and pay annually.

We record the first year's payment in the "likely" field on the opportunity/RLI. The service end date is how long the agreement is for (e.g. 3 years) So we need to record the payments for years two and three somewhere. 

We are using Sell Advanced (on cloud), Opportunities with Revenue Line Items. 

Can anyone share good practice on how best to record this information in the easiest way possible for users? Thank you!