Add remaining time left when renewing a rolling license to new expiry date

Problem/Motivation

When a user renews their license before it expires, the new expiry date does not account for the remaining time left on the current license when calculating the new expiry date. it simply adds whatever term the license is for to the current date.

For paid membership sites, it's good to give customers notice their license is expiring in XX days/weeks, and to renew it early to avoid any disruptions and so the merchant has continuity. However when they do this, they effectively lose whatever period is left on their current license and are short-changed.

Is this something that is possible? Thanks for the great module.