What happens when your user attempts to use the app without an Internet connection and it can't phone home to verify it's within the trial period or paid?
Only the first use would need remote access. Assuming that the user just downloaded from the app store, that should be fairly safe assumption.
After the initial connection is made and the trial started, the trial end date can be verified via remote connection but fallback to internal clock for the current timestamp.
As a developer I so miss this possibility. "Lite" apps and in app purchases are not the same as old school trial versions.
It's even worse for the Mac app store as trial versions have been around for decades on the computer.