Drivers Licence Sticker

Found this in an auction lot some time ago, and just came across it again. It's a drivers licence which belonged to a Regina RCMP Detective (I've crossed out his name and info, just in case he's still around).
What I'm curious about is the little sticker on the top left corner.
There's no denomination, so I don't think it can be called a revenue stamp. There must be a name for these.





How would you folks categorize it? Cinderella? Label? Garbage?

I'm not sure what is being validated - and for just one year. Any idea what is under the label that ends in "ed", like maybe "voided" and now validated?
I agree that it most likely is not a revenue stamp, but other than that, I am clueless.

I have not seen a Saskatchewan Driver's License (Licence) before, so I suspect the format of the license may have changed since the 1970s. Nevertheless, this may explain the sticker:

Holding it up to the light, I can read VOID UNLESS VALIDATED (You would think that would go without saying).
So I guess this is the validation sticker for the year of 1976-77 (April to April).
I wonder if that's what they're called, validation stickers?

I'm sure it merely indicates the fee has been paid for another year, so that you don't have to trudge downtown and get a whole new license; the "validation" stamp can be sent in the mail. Ohio does the same thing for license plates, sending you a self-stick stamp to apply over the previous year's stamp. My license plate has five or six such stamps applied, since around 2007.