Hello,
I've seen a few people do this so thought I'd also do the same! I've enjoyed Natural Cycles for over a year now. I'm not yet trying to conceive but I've enjoyed being off hormonal birth control and it's really helped me understand my body. NC become free after 10 referrals so I will remove this post if I ever get there! Currently the link will get you 20% off your first year and a free thermometer, I get closer to my lifetime free membership!
https://www.naturalcycles.com/refer-a-friend?name=THlkaWE=&code=referralid20&referral=iy00pd3pcxvpf3ti