[me_plus_one]

For the first time I have paid to remove adverts from the Ookla speedtest app on my phone.
This removed the adverts from the app on my phone.
I also use this app on my tablet but this still has adverts.

Do I have to pay to remove adverts per device?
If for whatever reason I was to factory reset my device will Google or Ookla remember that I have paid for the speedtest app with adverts removed?

[me_plus_one]

My devices run on Android for clarification.

[ShaunIOW]

Try uninstalling it from the tablet then re-install from your play store account.

[steffangl]

On iOS you pay once. I bought using iPhone 4 years ago, then pressed the button to buy on iPad but it said I had already bought this and removed the ads. Same when I got my new iPhone last year.

[Orbitalzone]

Most paid apps I've had on Android work on all my devices that use the same google account. I think some apps are per device only but most seem to work on all your devices, even after a factory reset etc.

[me_plus_one]

Checked app tonight without reinstalling, no adverts so I think my tablet has synced itself as its always on WiFi.
Good to hear this will likely be the case if I do have to factory reset.
Thanks for the replies.