Assuming you are running a blog and you want to encourage readers to support your blog via subscriptions.
Some blogs might offer membership content (only member who subsribe can access these content), but this article assume all content is accessible and subscription is just a voluntary way to for readers to support the blog in a long term manner.
NOTE: Refer to Setup Support/Donation Payment Link for one-time donation/payment.
Patreon
Patreon is all about: Building a membership platform for creators. - source
- Fees: 5% Patreon Fee, Processing Fees, Payout fees
- New Creator Plan starting May 7 2019: Patreon fee for Lite (5%), Pro (8%), Premium (12%)
PayPal Subscription
https://www.paypal.com/buttons (Select Subscription)
- Require a PayPal Business or Premier Account: Free
- Fees: 2.9% + USD 0.30 (US), 4.4% + USD 0.30 (International), fee might varried depending on Currency
Gumroad Subscription
https://help.gumroad.com/article/50-subscriptions-faq
- Fees: 8.5% + USD 0.30 (Free plan), 3.5% + USD 0.30 (Premium Plan/$10 per month)
Ko-fi Subscription
https://help.ko-fi.com/hc/en-us/articles/360005111213-Subscriptions-and-supporter-only-content-
- Require Ko-fi Gold: $6/month
- Fees: No