You can work upon one of the many tools that exist for this exact purpose:

1. You can use aMember to create a standalone membership website.
2. You can setup a Wordpress website and install a plugin like "MemberPress", "Paid Memberships Pro" or a combination of plugins like "Woocommerce + Groups + Subscriptions".

It all depends of what sort of interaction you want for your customers. Take a look at those options and see if any of them match what you are looking for.

Of course you can create something from scratch but that takes time and usually a lot more money. Make sure what you need doesn't already exist before venturing into a fully custom job.

Best of luck! Let me know if you have any more questions!

I've spent my career building these platforms. It sounds like you might be better off building your site on top of an existing framework that supports membership: that way you can continue to focus on your startup's differentiating value, rather than rebuilding the wheel with a membership system.

Several are available. Elgg (I was a cofounder) is now a programming framework designed to make it easy to build social sites. There are other good choices - it depends on the features you need on top of the membership functionality.

Let me know if I can help.

Consider using a third party solution like Kajabi, MemberPress, Circle.so, or MightyNetworks. MightyNetworks allows you to create a premium membership site for free.