Life expectancy according to some website said 5 years, possibly more. Females I believe can get fertile 3 times a year. Possibly 4, but the hoglets won't be healthy and you'll also kill the female in the process.
Why do you want to breed them? You cannot house them together for too long. How old are them? If you seriously want to breed them. You need to separate them. Try 1 - 2 months or longer, then put them together. Usually if you wake up around the wee hours you might be able to see the male 'harassing' the female (can be quite noisy). Keep them there for 2 weeks (as recommended by some breeders) then separate them again. Wait for 1 month plus to see kena or not lo. Before you breed them, you should also be prepared with a proper house for the female and the babies, don't be like me caught off guard, lucky my female friendly and don't stress easily or else bye bye to the babies. A very sad sight.

Mine 2 days kena already, not even 48 hours. zzz, now I have lots of trouble taking care of the bunch of hoglets. Hope you consider properly. 2 female reserved, 2 more males to go.