This is an issue that we have been dealing since the last 2 years. The in-house applications do stop working after 1 year. It is a massive exercise for an organization like ours to rebuild hundreds of apps and redeploy it on thousands of devices every year.
For us it is a month long exercise where we rebuild all our apps and inform all users to get new ones through the distribution channel. Still every year some users are left with non-functional apps.
I have filed an enhancement request with Apple(Bug ID#9848075) for this and am still waiting for a reply.
The above mentioned bug is closed now. Here’s the official response:
Distribution certs for enterprise are now 3 years in duration.