The membership fee for this service simply provides you with 'support'. (i.e. access to software, etc which is probably available for free elsewhere on the internet). The system uses the Gnutella P2P network, which is common to Limewire and other software.
Downloading copyrighted material through P2P networks is a civil offence for which you can be sued. However, the nature of P2P networks is that, while you're receiving files from someone else's PC, files on your PC are made available for uploading. The law regards this as 'distribution' which is a criminal offence, which can lead to fines or imprisonment. (In some circumstances, even downloading can be a criminal offence. This is when it is done on a large scale or in the course of a business).
Your membership of Download Music Inc, doesn't give you protection from the law. Their 'get out clause' appears at the bottom of their home page:
"Copyright: Download Music Ltd does not condone activities and actions that breach the rights of copyright owners. As a Download Music Inc user you have agreed to abide by the End User License Agreement and it is your responsibility to obey all laws governing copyright in each country".
Legal downloads are usually charged at, say, 80p per file. Some people might easily want to download 20 files a week or about 1000 files per year. That makes the legal cost of such files come out at around �800 per year. I've been on the committee of various clubs and organisations which have offered 'lifetime membership'. This is usually charged at between 10 and 15 times the cost of a year's subscription. Thus, it seems reasonable that any service offering a lifetime of unlimited downloads (if one existed) would be likely to charge around �10,000 for such a service. Any firm which claims to be able to offer such a service for a few pounds should obviously not be trusted.
Chris