It took me a while to figure out the whole offer/survey thing... I was a just click member for a while.
Keep it simple.

Under 1 year member - you get access... no matter if you do anything else or not. Keeps newbies visiting.

Over 1 year member - Did you earn more than $xx amount (not sure what seems fair - $100/year ??) then you get access for another year...recheck on anniversary of their join date. set bit

Over 1 year member - didn't make the cutoff point?? then probably recheck periodically for qualification (weekly? monthly?)

Can display a message for those who don't qualify. Would you like to learn how to earn more money?? visit our forum for earning tips... or something like that.

Hopefully this is simple to program and doesn't put much load on the machine.

I love how you are always updating the program... changing it, making it better.