Pro. This page is about Pro itself.
Pro is a one-time payment. You get every Pro feature for life, including every future update. There’s no subscription.
Everything else in this manual is free.

Unlock Pro on your computer. Your iPhone or iPad picks the key up with your vault, so you only do this once (see Reading Vault on your iPhone or iPad).
The section then says Pro is unlocked, with your key’s number, for example “Pro key #1042”.
Your key is checked on your own computer or phone. It never goes online, and it never expires.
If a key doesn’t work, a short message says why. Check you copied the whole key. If it still doesn’t work, write to me through the contact page, or email me at jhesch@gmail.com (the message shows the same address).
Your key works on your next computer or phone too. If it doesn’t come across with your vault, paste the same key again.
Remove key (in the Pro license section, it asks you to confirm) takes the key out of the vault’s plugin settings. Only use it on a device that no longer shares the vault: on a synced vault it turns Pro off on your other devices too.