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As for feedback, you can take those collected emails and send a followup email asking how the trial is going, with links to your online store, support pages,. I've done a variation of the following: you could add a questionnaire page to your website with a free whitepaper download in exchange for their opinion. That kind of thing. People really need inducement sometimes.
I've advocated for freebie rewards for registering the trial software, i.e. Free Templates or Ten FREE royalty free photos - no obligations, yours to keep just for evaluating our software! FREE.
That kind of thing.