What is the difference between the Free and Pro plans?
The difference between the plans is in the features. Both plans have unlimited links, affiliates, and referrals.
The standard free plan lets you create referral links with random IDs, which is sufficient for most basic affiliate programs. The links look like this: www.youstore.com/r?id=ie3ejs
The $39/mo plan lets you create "custom links". With these links, you can replace the random ID with a text of your choice, so you can have links like this: www.yourstore.com/hello
The $39/mo plan also lets you generate unique discount codes for your affiliates, that they can use to generate referrals. This means affiliates can share a discount code with their followers and if that code is used at checkout, the customer will get a discount, and the affiliate will get a commission.