The token expires in an hour — and that is normal
Etsy's authentication works differently from other marketplaces. The key you provide is attached to every request, but the token that actually grants access lives for one hour only. The refresh token that comes with it is valid for 90 days and renews the expired access token on its own. So the answer to "do I have to reconnect every hour?" is no — the refresh happens in the background.
The thing to watch: if no sync happens at all for 90 days the refresh token lapses too, and you have to re-authorise the connection. On an actively used shop that does not arise in practice; it can surface when reopening a shop that stayed closed for a long stretch.