Activation
A license key turns LadderIDE from Sim mode into Pro mode, which adds Arduino code generation and upload to the board. Everything else — the canvas, the tag database, the simulator — works the same either way.
Entering your key
Your key arrives by email when you buy, and it is also on your order page in Lemon Squeezy's customer portal. Enter it in LadderIDE and the application checks it online once: if the key is valid and has an activation left, that machine is activated and stays activated — you do not need to be online to use Pro afterwards.
Until a key is entered, LadderIDE runs in Sim mode. Nothing is time-limited and nothing expires; Sim mode simply generates no Arduino code.
How many machines
A key covers a limited number of machines. Your order page shows the limit and how many activations you have used, so that is the place to check before you set up another computer.
Moving to a new computer
Deactivate the old machine from your order page before activating the new one, and the activation is returned to your key. If the old machine is gone — failed drive, reinstalled operating system, sold — write to [email protected] with your order number and we will reset it. This is not a problem you have to argue your way out of.
Which versions your key covers
Your key covers the major version you bought, including every update within it. A future major version is a separate release and may need a new license.
Because there is only one installer, a later major version will install and run quite happily with an older key — in Sim mode. If that happens, LadderIDE says so explicitly rather than quietly dropping the Pro features. Your projects open either way.
If it will not activate
Check the key against your order page first — the most common cause is a truncated copy-paste. If it is correct and still refused, or if the activation count looks wrong, email [email protected]. And if LadderIDE turns out not to work with your hardware, the refund policy is 14 days from purchase and activating your key does not disqualify you — which is the whole point of buying a $49.99 tool you could not fully try first.