Square WebPay - Avoiding Token Expiry
Manual Prevention
A couple of times a week, go to Admin > Modules > Payment / Square WebPay, click Edit then click Update.
Automated Prevention
Set up a cron job job to run at least twice a week (daily is fine too) that refreshes the token.
Depending on your server configuration, you can do
php PATH_TO_STORE/squareWebPay_handler.php
(where PATH_TO_STORE is the value of DIR_FS_CATALOG
from your includes/configure.php
file)
or
/usr/bin/wget https://YOURSTORE/squareWebPay_handler.php