Always read the fine print. That’s the lesson Cadillac Super Cruise users are about to learn.

First reported by Motor Trend in September, Cadillac’s Super Cruise hands-free driver assist systema Level 2 system—comes with a three-year trial before requiring a subscription for continued use.

For the earliest adopters, that trial is about to end. Super Cruise was first offered on the 2018 Cadillac CT6 (it was standard on the Platinum trim and part of a $5,000 package on Premium Luxury models), with vehicles arriving in showrooms in September of 2017.

Cadillac spokesman Stefan Cross confirmed to Motor Authority the original trials are about to end and owners are being notified on 30 days before the three-year trial expires.

Cross told Motor Authority that 2018 CT6 Super Cruise owners will get an extra year on the initial three-year trial.

“Looking at the original disclosure and current disclosure, both say owners will need an active Super Cruise subscription and OnStar plan,” said Cross. And it was displayed on the window sticker under the Cadillac Owner Benefits section.

Super Cruise is more than the hardware embedded into the vehicle. “Super Cruise requires both OnStar and connectivity to operate,” Cross said. The mapping data and updates all require a connected service plan.

Cross said customers can purchase a stand alone Super Cruise plan for $25 per month or add Super Cruise to certain OnStar bundles for $15 per month.

“At this point customers will have the option to renew to keep Super Cruise working properly or let it lapse,” Cross notes, with different pricing options for customers, including a standalone subscription option. “It won’t be a one-size fits all.”

Super Cruise received a large update in 2019 that allowed it to work on 200,000 miles of highway in the U.S. and Canada. The update added 70,000 miles of map data to the CT6 sedans that featured Super Cruise.

When the system arrives on the 2021 CT4 and CT5, along with the 2021 Escalade, it will gain the ability to change lanes with the tap of a turn-signal stalk.

Update: This article have been updated with Super Cruise subscription pricing.