How to create payment packages for my site members

You can first offer these packages using Wix pricing plans .

Displaying these on a page for members to purchase, and then coding it so on payment successful, you add a certain number to a database with their info. So for example if I purchase the a plan with 5 credits, my user email and credits are added to a database.

Here is some example code on how it could be done.

import wixPaidPlans from 'wix-paid-plans';
import wixData from 'wix-data';

$w.onReady(function () {
$w("#button").onClick(()=> {
    wixPaidPlans.purchasePlan("planId") // you can get the plan id from the paid plans db
    .then((results)=> {
        if (results.wixPayStatus === "Successful") {
            let toInsert = {
                email: "userEmail",
                credits: 5
            }
            wixData.insert("DBNAME", toInsert)
            .then((res)=> {
                console.log(res)
            })
        }
    })
})
});

Here are some more helpful links -
Wix Data
Wix Paid Plans