No, you can sign up for one of many free trials for around a month of time. If they do not satisfy you, you can easily cancel your subscription, not having paid a single cent. You will still receive valid credits from the company you chose for your free offer.

Many of the offers can also be subscribed to for a sum of money (for example, a trial month of Blockbuster Online will cost $9.99 USD, and let you rent as many DVD movies as you want during that period of time).

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram