You may follow this guide to make the password be remembered for more or less time via the macOS keychain UI. As mentioned in the doc:

GPG Suite preferences pane (old name: GPGPreferences) password section also has the option to set a certain time your password can be cached. Enter any amount of seconds for which you want your password to be remembered. Password queries after that time period will again show pinentry asking for your password.

However, keep in mind that it seems you can't make your GPG password be remembered for a longer period of time than 99999 seconds. If you'd like the password to be requested after an even longer time you may consider removing completely the password if that suits your needs better.