Offline Grace
A fair question before you trust any licensed plugin: what happens if the licence server goes down, or your host has a network wobble? With a lot of plugins, the answer is that your server stops. With ProtonAuctions, it does not.
Checked once, then trusted
The licence is checked when your server starts. On a successful check the plugin saves a signed proof of that result, tied to your machine, so it does not have to keep asking.
Days of grace, not seconds
If a later check cannot reach the licence server, the plugin falls back on that saved proof and keeps running normally for up to seven days. That is plenty of time for a network issue or a licence-server outage to pass without anyone noticing. Only if the plugin stays unable to check for that whole stretch does it wind down, and even then your data is untouched and waiting.
Right after an update
The saved proof belongs to the version that earned it, so a new version checks with the licence server the first time it starts. If the server cannot be reached at that moment, the plugin still starts on the old version's proof, as long as that proof is within its seven days. Buying, selling, bidding and accepting trades wait, and so does an auction with bids that reaches its end time. Players are told that auction functionality is currently disabled, and /ahadmin license shows WAITING. The plugin asks again every minute and picks up on its own as soon as the server answers, with no restart. Auctions that ended in the meantime then settle straight away.
It cannot be faked
The saved proof is signed and verified inside the native core, and it is tied to your machine, so it cannot be copied to another server or edited to say something it should not. The grace period is a safety net for honest owners, not a hole for crackers.