Ruleset for Google Tag Manager (GTM) to fire any tags once per session/day/user.
Currently only Google tags (like Doubleclick) have options within GTM to choose uniqueness of a pixel firing. The idea of FOnce is to give the ability to fire any tags or pixels you need uniquely.
Note, that a session in terms of FOnce is not the same as a Google Analytics's session. FOnce operates following idea of session: set of pageviews with an interval between seperate pageviews not more than 30 minutes (or whatever you set in the "FOnce - Session lifetime minutes" variable). This is pretty close to what Google Analytics consideres a session, but not totally same. There will be some discrepancy. I'm open to any suggestions how to improve this or any other part of FOnce. Please, write your suggestions to 42@stony.me.
FOnce is made for GTM v2. Though it will work in GTM v1 after some simple tweaks (which will require some GTM knowledge from you), I recommend migrating to v2 if you haven't done so.
Import file FOnce.json to your GTM container using merge option (screenshot: http://joxi.ru/l2ZVPD5uX0bD2J).
Use rules "FOnce - Once a session", "FOnce - Once today", "FOnce - Once a user" to fire tags you need.
If you need to add more conditions (say, fire not just once a session, but once a session only on a specific page), you do simply like it is said: add a condition to the FOnce rule you are using.
Note. If you just add another rule to your tag, that won't work how you expect (in this case your tag will fire 2 times: 1 for each rule, but not when both rules are met at the same time). So, for example, this http://joxi.ru/GrqenNbiDppWrz will fire test_tag 2 times: on the first pageview of the session and when foo-page will be opened. Instead you need to add second condition to the rule "FOnce - Once a session", like this: http://joxi.ru/8An0RyJu4bBVmO (don't forget you need to turn on "Page URL" in Variables section to see it in the list of conditions).
More about FOnce including use cases - in this article: stony.me/fonce/