Behavior for Shopping Cart?

[SaranacLake]

Hello.  I could use some advice on the best way to handle my shopping cart.

My website will sell subscriptions along with more traditional items like books, t-shirts, etc.

For subscriptions, I have these business rules...

1.) Only non-members can purchase a "trial subscription".

2.) Once you are a "member", then no more trials for you!

3.) You can purchase multiple subscriptions (e.g. into the future), BUT I only allow you to purchase ONE subscription at a time.  (My system would allow multiple purchases at once, but I don't ant people accidentally signing up for 2 years and then i have to clean things up.  Also, I want the transition from a "trial" to a "full paid" subscription to be clear.)

4.) if I ever offer multiple "trial" offers, then you only get to take advantage of one, and then after that it's on to full paid subscriptions for you - although I will run "promos".

 

Here is the problem...

Nothing stops a non-member (or a member) from adding a "paid" and a "trial" subscription into their shopping cart.  Or multiple "trial" subscriptions.  Or multiple "paid" subscriptions.  (Maybe someone adds a paid subscription on Friday, then the weekend comes, and on Monday they notice the trial subscription offer and add that forgetting about the paid subscription.)

Or maybe someone is trying to "game" things, and adds 3 "trial" subscriptions and tries to check out?!

 

How should my website (gracefully) handle these scenarios?

 

1.) Am I aggressive up front, and prevent people from adding a 2nd subscription to their shopping cart as they shop?

2.) Or do I allow them to go wild while shopping, but then address the issue at checkout?

3.) Should my code be doing the work, or is the onus on the user to go in and clean up their shopping cart?

4.) If I address this issue at checkout, then do I need to add extra functionality to adjust their shopping cart from the checkout page on-the-fly?  Or do I send them back to their actual shopping cart page and make them clean things up there?

5.) What do I do if someone has already added other items to their cart previously (e.g. T-shirts).  Do I handle the "Get this offer" separately hoping to get them signed up ASAP, and then leave the T-shirts in their cart to purchase later?  Or do I handle everything at once?  (If they just have a "trial" subscription and a T-shirt, no worries.  But if they have a "paid" subscription and then add a "trial" subscription and are looking for a quick checkout, then the scenarios/concerns above come into play...)

 

The stuff I was asking about last night is what got me to thinking about all of this.

The flow was supposed to go...  User sees "get one month for $1" on the home page, clicks the button, gets a trail-offer details paid, clicks "Get this offer", and wah-lah, they are on the checkout page!  But if they already have things in their cart or maybe click the offer button 10 times, then things get messier.

My concern is that converting a user to a paid member is the #1 goal, and I don't want other things to get in the way, whether that is a complicated checkout or things getting distracted purchasing other things like T-shirts!  At the same time, if you want to buy multiple things, all the better as long as you follow my business rules.

 

So what's the best way to not be a pain to shoppers, but to maintain the rules I mention above?

 

Edited September 9, 2020 by requinix
edited at author's request