how could I understand this rule?

The 1-year extension provides access to support and updates for a year from the license's current support/update expiration date (or from the date of purchase, if the license is not active). Please note that your license must be up-to-date to access certain licensed customer areas, such as ticket support.

If I bought one year forum license in year 2016.1.1 , then in 2017.1.1 I didn't renew untill 2017.6.1 , so I renew in 2017.6.1 my license validity to 2018.1.1 or 2018.6.1 ?