I bought sync pro and have sync for lemmy installed; there’s no way to activate pro right now, and afaik that option is not coming.
Presently you can buy a permanent ad removal in-app for $20, you can subscribe to sync ultra for $17/yr, or you can use it free with ads.
It’s a good app, and the dev absolutely deserves to make money. If I understand correctly, developing sync is his full-time job. The prices are definitely steeper than with sync for reddit, but Lemmy is a much smaller community. He can’t necessarily expect as many sales.
In the lemmy community someone said that a one-time Pro version is coming later, once the app leaves beta
No that’s the lifetime subscription. If you only want ads-free it’s about 15euros.