Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: why does it need a subscription?
Document: I am happy with this product for the most part.I was initially told by a sales associate that i did not need a TiVo subscription, but that turned out to be false.After getting a subscription, I have to admit that I am very happy with being able to record 4 shows at once. As a TV-Holic, I am very please.
This may be my last one before I completely bail out of the TV market. Just about everything I'm interested in can be found elsewhere on the internet. In addition, the customer service at TiVo has gone downhill -- have you every tried to cancel a TiVo subscription? It's pretty funny. If you need to cancel, just keep saying &#34;I want to cancel&#34; until they transfer you all the way to the last person, who will eventually do it.
We purchased this because we've decided to axe the whole cable thing and go with an HD antennae. I like to have tv but don't need 500 stations at $100+ a month through a cable or satellite company. I also don't like my son to watch commercials so we thought the Tivo DVR would allow us to purchase a DVR outright and get what we needed. But alas TIVO charges a monthly service fee. $500 for a lifetime subscription (yikes!)
subscription required
This is the perfect DVR for recording up to 4 channels from my over-the-air antenna. And there is no cable subscription required!
Still I do not like to have to have a subscription but I guess this is how TiVo can make there own rules with no competition.
did Not realize you needed To purchase a subscription To tiVo To use this item which makes No sense To me. very disappointed and will be returning.
This was a refurbished unit. Hidden cost is a monthly subscription that eliminate any advantage against similar product provided by cable or satellite providers.
... that you had to buy a new subscription for the Tivo service! I had a previous subscription with my Tivo premiere so I decided to keep it and return this one!
I enjoy using my Tivo. It was very easy to setup and is a breeze to use. I just wish the subscription service wasn't so expensive. It work well, but the cost! ?
Answer: For what the device physically does, it wouldn't need a subscription.  It records whatever comes through the antenna (digital antenna or cable).  But because TiVo would like to continue to make money off people every month, it's built in software that actually tells the device to record shows won't work without a subscription.  The software has info for all the channels that come in- what shows are playing at what time, details about each episode, etc...  It allows you to record shows how you want (every week, only new episodes, all episodes, etc...).  There are also apps like Netflix, Hulu, Amazon Instant Video, and such built in.  This is a nice feature for me because I have a Netflix account.  So while it is a bit frustrating to have to pay a subscription fee for hardware that doesn't really need it, you are actually paying for the software to control it, which gives you some nice features.