There are a number of excellent apps that you can use to easily create a loyalty program for your Shopify store. A loyalty program can really help to encourage repeat purchases from your existing customers.
Pricing for loyalty apps varies:
some apps offer a free version and some don't.
some pricing plans allow a certain number of orders per month and some charge by the number of members in your loyalty program
Here are 2 great loyalty apps that you make like to trial: