The "trial" status is a relatively fuzzy concept. It would be hard to specify it so precisely so that a "tool" can be built for it.
What option?
Locally installable software:
Legal restriction. Full functionality is give right off, but the user should willlingly stop using it after the trial period is over. Basically, protection by trust (for private users) or protection by legal prosecution (for company users).
Restricted functionality. Users can download a lite version. Whenever they decide to come to the full one, they request some license key that unlocks the rest of the functionality. Alternatively, you provide a secret download link for a full version. Even better, if you create watermarked binaries so you can track unauthorized usage/distribution to its source.
Web software:
- Trial or full is a matter of activated features in the users account. As all users access the application via web, nobody has the software copy to install it in an unauthorized way. Each users works with their own account and has access to only features which are granted to them.
