Most (non-geek) people think that shareware is a type of software. Well, actually is not a type of software, it’s a way of marketing software. From the vendor’s perspective it looks like offering a 15-30 days trial should be more than enough to test the product and buy it before it expires. But even with a trial period:

• Some of the users will request a refund after the purchase saying the product is not doing what they need even after they tested it in the trial period;
• Some of the users are not convinced to buy the product in the trial period.