How long can I go before I have to rebuild the app to my watch? This is one of those things I'd love to install and play around with like, twice a year, but I

How long can I go before I have to rebuild the app to my watch? This is one of those things I'd love to install and play around with like, twice a year, but I suspect I have to reinstall it every 7 days to keep it working unless I pay an Apple dev tax.