These unusual oval stickers expired at the end of February the following year (indicated in small print).  In 1971 and 1972 the license plate number sometimes appeared on the stickers.

The 1971 sticker was a bit different in that it was issued to show that the car insurance had been paid (the plate already carried the 1971 date). In 1972 someone was pulled over for using a Chiquita banana sticker in place of the normal '72 one. At a distance the two stickers are hard to tell apart and he had many fooled for a while.
 

Manitoba was the last province to introduce staggered registration.  Up until that point, all stickers expired at the end of Feb (of the following year).  When staggered registration was introduced, the day of the month was placed in the left hand sticker box.