The following is from the Torah dot org website:
QUESTION 15: HOW STRICTLY SHOULD ONE ABIDE BY THE ‘TRIAL PERIOD’ OF SHAREWARE SOFTWARE
QUESTION
Some software that can be downloaded for free from the Internet comes with a provision that it is free only for an “evaluation period”, let’s say for thirty days, after which the software must be bought or destroyed. How strictly must one abide by this provision?
RABBI BELSKY’S ANSWER
If a person needs more time for the evaluation period, I’m sure the company will not mind. It can be thirty-one days, or thirty-five days — as long as it is still an evaluation period. When a person takes something for evaluation and keeps it, it is, as Rabbi Moshe Feintstein said, echt gezel (genuine theft).
I tell people constantly that no real success will come from something a person takes — a book, or anything else — that a person could buy, but which he figured out a way to get without buying. The person who produces the item wants to sell it. Typically the justification that the person who wants to use it gives to himself is that he wants to use it for some grand purpose. But think: what value does a grand purpose have that was achieved through gezel (theft).
QUESTION
There’s something called “share-ware” where a person is supposed to pay a $20 registration fee. I think the estimate is that not more than 5% of the people who use shareware actually pay for it.
RABBI BELSKY
But that doesn’t make it right not to pay for it. If a person steals, he affects himself; the act affects his soul. You can’t steal something and then hope to be the same person afterwards (emphasis mine – icot.) It is important to appeal to people on the basis of themselves.
QUESTION
So it is also between a person and himself?
RABBI BELSKY
Yes.