Get user subscription through REST API endpoint

You can loop through your subscriptions and see if the order.buyer.id matches the member ._id and is active

import { currentMember } from "wix-members-frontend";
import wixPricingPlans from 'wix-pricing-plans-frontend';

$w.onReady(() => {
    wixPricingPlans.orders.listCurrentMemberOrders().then((orders) => {
        getMemberInfo(orders);
    }).catch((error) => {
        console.error('Error Getting All Orders')
        console.error(error);
    });
});


function getMemberInfo(orders) {
    currentMember
        .getMember()
        .then((member) => {
            checkForMemberShip(member, orders);
        })
        .catch((error) => {
            console.error('Error Getting Member Info')
            console.error(error);
        });
}

let hasActivePlan = false;

function checkForMemberShip(member, orders) {
    console.log(member._id, orders);
    for (let i = 0; i < orders.length; i++) {
        if (orders[i].buyer.memberId === member._id && orders[i].status === "Active") {
            hasActivePlan === true;
            console.log(hasActivePlan);
            break;

        }
    }
}