I also purchased the lifetime no-ads option, and now get ads. Support says you have to buy a subscription. This is a widespread issue that seems to be affecting most if not all users. If you check the reviews on the play store there are many hundreds of 1 start reviews over the last few days and the app rating has dropped from 4.2 to 3.7.

A thread was also pointing out in the google support forums for another app that did the same thing, ignoring a no-ads purchase and forcing a new subscription, and google asked to report the app from the store as this violates their terms of service