Working Hours is made by one person, who also answers the email. Write to cosminiulian1998@icloud.com and you will hear back from the person who wrote the app — usually within two working days.
Before writing about a wrong total: Settings' Email a bug report… attaches two files to the message — the app's log and a backup of your ledger. It is the only way to reproduce a ledger, since none of it leaves your phone otherwise.
Use of Working Hours is governed by Apple's Licensed Application End User License Agreement. The unlock is a one-time purchase, yours to keep on every device signed into the same Apple account; use Restore purchase on the unlock screen to bring it across.