I’m checkin this out right now

In my mind, I can't checkout, because it's a noun or an adjective. I always do verbs, so I check out.

You can check-out any time you like, but you can never leave

But: Log in... Login... 🤔

(pretty sure "Login" is a word... right?)

Checkout is a noun. It's the registers at the end of the grocery store.

Checkin is also a noun. It means the front desk of a hotel.

Once you start verbing either of those, you need to split the words up. I don't know why, I don't make the rules.

You can check-out anytime you'd like, but you can never leave.

Checkout is a noun. You can only check out.