Yes it is possible.
You can set up a start up script that logs the date in a field the first time it is opened. There after, the same script can compare the current date to the date in the field. IF the difference in days is 30 or more and Get (accountName) returns the name of your "trial" account, the system can ask the user to pay your for access and shut down the file.
You may also want to "cripple" the file by counting the number of times the file is opened instead of checking the date so that they can't spoof the file into opening by changing the date on their computer's system clock.
Thank you. Do you know of an example script I could see that does this?
I like the idea of only allowing a certain of "opens." I think that would work better for my application.
Set Field [ globals::OpenCount ; Globals::OpenCount + 1 ]
IF [ Get (AccountName ) = "Trial" and Globals::OpenCount > 30 ]
Show Custom Dialog [Please register this software so that you can gain legal access to this file."]
This assumes that you use Manage | Security to set up an account named "Trial" as the one to use when using the file during the trial period.