What WordPress plugins (especially free ones) would you suggest for running a site offering subscription content?

As every membership site is unique in its needs & requirements, it's a hard question to answer with one plugin. I would start with Paid Memberships Pro (which is free) and consider alternatives based on your site's needs.

MemberPress is the easiest to use but its not free and has its limitations. But 'Paid Member Subscriptions' is a nice little plug in and you can start with a free trial to see if you like it and play with the features. Personally I think Wild Apricot is the best option, its cost effective and has most of the feature you will ever need. Its not a plug in though, its a stand alone butttt it incorporates very nicely with word press. Hope this helps.

Here's an option:

https://appsumo.com/wishlist-member/

WordPress membership plugins allow merchants to charge customers for access to digital content such as a course, subscription content with recurring billing, and even access to an exclusive community.

Here is a list of membership plugins for WordPress. Most of these plugins offer a variety of features — https://www.practicalecommerce.com/11-WordPress-Plugins-for-Memberships-Subscriptions

Jetpack has over four-million active installs, but many WordPress users still do not understand what it does or how they can use it to improve their website. Think of Jetpack as the ultimate toolkit for your WordPress website. Because WordPress takes some of the load from your server, it will help your site run smoothly despite the extra features.
You can read more here: https://neilpatel.com/blog/free-wordpress-plugins/
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath