I'm sure that the dates they give are conservative -- if an implant is said to last "5 years" it must give you more protection than that. It's not like at 60 months and 1 day it suddenly stops working (if it is still in your arm). The drug company will label it on the side of caution, so nobody will sue them due to getting pregnant at 4 years 11 months 15 days or whatever. But just how long one could go past the advertised effectiveness date and still have it work is probably not known. If a pregnancy would be a disaster, I'd hesitate to rely on it by now and would start to use some kind of back-up protection like condoms.
I think the best answer you can get is from your medical provider .
To remove the Norplant cost between $100-200. If you have insurance, the insurance will cover for the removal..
I believe you can get pregnant when the Norplant expired. If you are not plan to have baby.. you need to take care of this right away... and get another method of BC... If you are trying to conceive... then you need to remove Norplant instant...
Good luck to you