Hello
Yes, these articles were written a long time ago. But the idea of how payments and payment related apps are working in UNA wasn't changed.

If you want to sell products in Market or Paid Membership Levels then you just need to configure necessary payment provider(s) in Paymants app and products/levels in related apps Market/Paid Levels. In case you plan to sell subscriptions via Stripe you would need to create associated Plans in your Stripe account. The process is described here.

I hope to create membership page. 

You need to go to:
1. Studio -> Permissions and create your custom membership level(s). You may use Premium level which is available by default.
2. Studio -> Paid Levels -> Manage and create payment options for necessary Membership Level(s).
That's all. Your members would be able to purchase membership levels on https://www.your_una_site.com/page/acl-view page. It can be found in User End -> Account popup -> Settings -> Membership.

If you want to use custom purchase page like our Pricing page. You just need to create the page and a block (HTML or RAW) via Studio -> Pages builder. The block should have your custom design and use JavaScript calls from https://www.your_una_site.com/page/acl-view page.

Good luck!

Anton L thanks for the information!

Regarding a reoccurring subscription to the default Premium level. I have set everything up, and I'm going to make it public on my site soon, but just before I do that, I have few a questions. 

(1) If someone becomes a subscriber ($1 per month, reoccurring), is code in place to prevent the user from subscribing more than one time? Like, will it tell them "You are already a Subscriber" or similar message?

(2) Which Profile will the reoccurring purchase come from? For instance, I have a main Admin profile and I also have a site profile. I can take PayPal payments from both profiles/account (they both use the same PayPal account). If someone makes a reoccurring purchase to get Premium membership, does the payment go to my mail Admin account, or to the account I set up as an alias for the site? Or, does a monthly reoccurring purchase to get Premium membership have anything/nothing to do with either admin profile?

(3) If I go into either of my Profiles on my site, and I +Add Product, there is no option to add a monthly reoccurring purchase to get Premium membership here. So, is this +Add Product only for things like digital file purchases and not at all associated with reoccurring purchase to get Premium membership Level of my site?

I hope you can read my messy logic :) thank you for any reply!