Is GlassWire buy once or it's a subscription?

Hello,

After the end of my trial period, I wanted to buy GlassWire, and has mentioned everywhere on the buy-glasswire (even in the url). This look like a buy for once and you got it.
There is no mention of any subscription or anything.

But on the next page, when trying to buy it, I see this mention:
“This is a subscription product with a fee of $39.99 per year. You may cancel your subscription at any time…”

So I wanted to know if it was a buy once product or a subscription.

Thanks

https://www.glasswire.com/subscription-help/

Please check out the page above for details on how to buy GlassWire along with a detailed explanation of why we have subscriptions.