As we have often mentioned here players who spend any sum of money on the game lose their ads.
Just before the final rounds of All Stars I tried to get rid of ads in my competing game by spending 99p on a generous offer. Some of you may remember that I reported then that to my surprise it did not work and I kept the ads.
However this week my game has been updated to the new ugly skulls and colours I now no longer have any ads, and judging by many posts in Support the same has happened to many others. It is apparently a delayed regrouping of "test groups". This may be a deliberate delay to make it less obvious to players that the purchase caused the loss of ads.
To make it clear: I had all the ads features for about ten months of playing and made one purchase April 12th. So I would still conclude that my game lost ads because of this, just with one month delay.