How do you send a discount code to everyone who comments a word?

Tag the contact on the first send and check that tag on the trigger, which is what turns a reply into a one per person offer.

Three parts to get right:

1. Sending. Comment trigger, keyword SAVE with the equals mode so it does not fire on "saved this" or "save me a size". Private reply with the code and a button to the shop.
2. Not repeating. Add a tag like bf-code-sent as the last action. Add a condition at the top of the flow that ends the run if that tag is already there. Without it, a person who comments three times gets three codes, and on a post that does well that is a real number.
3. Counting. The tag is also your count. The number of contacts carrying bf-code-sent is how many codes went out, and it stays accurate whether the post ran for a day or a week.

Two things that catch people out on a big post. The private reply is allowed only within seven days of the comment, so a post that keeps getting comments in December will stop delivering to new commenters from the original burst. And if you use one shared code, anyone can screenshot it, so if that matters use unique codes from your shop and read the next one in with a request step rather than writing one code into the message.

The comment to DM flow is the base to copy; adding the tag condition is the only change.