Yeah. I was actually going to sign up for the membership.
While under the free trial, I tried to access the Express account section of my Instacart account online, and discovered that when you click on the Express tab it goes straight to some static page - saying "choose your plan." It was the only thing on the page. It was there to try and force people to sign up. You couldn't cancel the membership even if you wanted to. So I contacted customer support and the agent kept saying "well I can see your express membership account." I cancelled it because they were trying to scam and take people's money without their consent.
You should always have the option to cancel and it shouldn't be hidden so that the consumer is blocked from viewing their account. I filed a scam report with the Better Business Bureau.
Saw thousands of complaints. They shouldn't be in business.
User's recommendation: Do not sign up for the membership. Its a scam. Use another delivery service.