@all.. Whatever development Tools (Say VS 2008 ) you get under this program carry Lifetime License, So they will not expire after particular period of time. But as per EULA they should only be used for educational purposes and not for commercial use.
After verification the eligibility to download softwares for free remains for 12 Months, After that one will have to reverify. Even if you choose not to reverify, Tools you downloaded earlier remain valid. but you will not be able to download new tools.
You also get a Trial (12 months) Membership of XNA Creators Club, So you can also develop games for XBOX 360. To Know more about
XNA Creators Club Membership Visit
Here.