How about this: whenever you want to cum, you have to have something in your ass.
Get an average of how many orgasms you had per week in the last months.
If it's <10 per week:
You get one "free choice" orgasm per week (so you can put whatever you want in your ass for it), for any additional ones you have to sit on your purple plug for some time: 10 minutes for every orgasm you've already had this week.
If it's >10 per week:
Same as above, but you get to start with three "free choice" orgasms. For any additional orgasm, you'll have to either follow the rules above except add 5 minutes per orgasm, or fuck your ass with a dildo while edging once for every orgasm you've already had this week before you're allowed to cum.
Bonus rules:
For every tongue or dick/strap on (worn by another person) you've had in your ass any given week, you'll get one free orgasm next week.
While having sex with someone, you're free to cum if your ass is filled by something, but this Orgasm will count as five for your masturbation counters.
At the end of every week, track the amount of orgasms you had in a blog post, and if you wanted to cum more but couldn't
Have fun