You have to take and pass the test to get your license initially.   

Then you must attend a class every year to keep it indefinitely or you must retest after 3 years.


For example if you passed the test last year (2020) your license is good 20,21,22.   If you don't go to a class in both 21 and 22 you have to retest in 23.

If you attend class in 21 and 22 and 23 your license is good until you miss a class.


I prefer to retest every 3 years.   Takes less time and its cheaper.   That is until you forget to go take the test when its nearby and end up driving 200 miles to take it but I suppose the same thing could happen with forgetting to go to class also.