Can I use Mechanical Turk for a longitudinal study?
The best way to set up a Mechanical Turk longitudinal study is with TurkPrime.com. You can follow-up with users and invite them to take a new survey. As long as they are properly incentivized they will come.

I recommend that you inform them at the start that you are running a 10 part study and that those who perform well on each of the 4 minute studies will also receive a significant bonus, say $5-$10.

See here for some more instructions on setting this up.