Just an FYI, not that it really matters but, both AMT and requesters suggest copy/pasting you ID, as opposed to typing it, that's why they added the 'auto copy' thing on the last major update. So, some of those boxes will be disabled for regular text entry and only allow copy/paste. It's not often but, they always suggest trying copy/paste. But, typing is okay most times.
Yeah, it's hard to know when a study will get pulled. But, in the HIT description, you can see the maximum time that it may be up, if it doesn't get completed or pulled first.
"Qualification Test: Image Categorization
Description
You are invited to take a qualification test for Image Categorization
HITs
1
Created
4h ago
Time Allotted
120 Min
Expires
in 5d"
But, to reiterate, it could get taken down by the requester at any point.