Comment by jwrallie
I used it to get my Amateur Radio license, since a superset of the questions that can be in the test are public.
I downloaded an existing deck and modified it so that only the correct answer is shown instead of multiple choices.
I still can remember some of the content even though I deleted the deck short after receiving my license.
HamStudy.org is exactly this, an SRS site/app that already has the questions and some explanations to go with it (the site is free, but they also have an app which is a couple bucks and almost the same but in my opinion slightly better). I used that a couple months ago I studied for the technician class license and got a perfect score when I took the test. Then I studied the general class license and got one wrong (34 out of 35 = 97%. You only need 26/35 = 74% to pass.) I could probably go for the third one next but maybe it would be more useful if I actually go get a radio and start using it first.