Beware!
No, there isn’t any way in the app to pay to disable the ads (nor would it likely work anymore, even if there was). Sadly, this app is currently very broken, and unlikely to be fixed.
open app -> search on a word -> an ad instantly opens *in Safari* -> switch back to the app to try to read the search result -> instantly upon switching back to the app, before it is possible to read anything, the app immediately opens another ad *in Safari*...
The only way to sort of view the search results that were produced, is indirectly, from the iOS app switching mode, before actually trying to switch back into the app from Safari.
There is no way to actually get to the search results to tap on them or otherwise further interact with the app, without simply closing the app out entirely from the iOS app switcher.
Note that this dysfunctional behavior was not what the developer originally intended: it is a result of (now long-standing) ad server changes by the ad serving network the app uses.
This formerly very useful app has not been updated in many, many years, so unfortunately it appears unlikely to ever be fixed.
Don’t waste your time.