How long is a member supposed to be subject to them?

@Deby you can go to your profile and under Change your site preferences you will see "Disable ads on the site?" you can click to not see the ads.

I believe that you have to make 100 contributions to the database before you have the option to disable ads.

Yes, you must have contributed at least 100 items to the database are can disable ads. From, April 2015:

"To disable the ads, go to your profile then click on your site preferences. In the list of preferences you will see "Disable ads on the site?" and you can choose Yes and then save it. If the option does not appear on the site, then you're not eligible for the feature."

So who is eligible? Simply put, everybody who has contributed at least a hundred different things to the database. That includes images, comments, and databox proposals. If you've been active in the database then you probably have this feature enabled.

Hmmm... I can't find it.

Daisy, go to your profile and click on Settings. Then you will see the Preferences. It is the 9th item down on mine. I don't know if they're all the same or not.

If it doesn't show up for someone as Karen described, it means you haven't hit that 100 mark yet.

Thank you everybody. I'll have to add more to the database.

Still don't see it; at 100 images and 1 misc. proposal.

@dave can confirm but I do believe the site does an update every evening so perhaps anything that you added today to that database count will be updated then to give you the disable ads option from your setting page.

Thankyou Sue, will check back later.

I'm ad free!

Congrats, Deby! I didn't even notice them when I was new, but I'm glad you're ad free now.

I found them distracting; in a way they reminded me of watching regular TV.