Fairly common. JetBrains started that way too. Will they one day have a major version that's using a subscription model? Perhaps. But they will likely not regret this too much.
Where does it say that?
That is common and it is the model I use for my own software. But that isn't what I understood from their website.
Home page: "Pay Once, Use Forever. We hate needless subscriptions as much as you do. TextQuery comes with a perpetual license with free updates."
Pricing page: "Perpetual license Lifetime updates"
Which strongly implies every update is free, forever.
I hate the subscription model but I do recognize if they continously update the software, they'd like to get paid to do so.
Absolutely. Just make it clear.