I download software for trial use. If it holds back any features in the free trial, I never purchase it. If it does not give a long enough trial time to test, and then retest its performance, I do not buy. I consider the holding back of features, or the lack of time to evaluate, or become dependent upon its services a reflection that the features are not ready for market, or the novelty and productivity or indispensable qualities of such will not be proven over time.
If I try it, and it proves its benefits go beyond short term, then I buy it. The trial period should confirm, reconfirm, then provide a relationship of economic, or productivity dependancy. It then, as they say, sells itself.
You do not always get what you pay for, but you never get what you do not pay for.