Common in test equipment
Test equipment is expensive because the market is relatively small.
I am not talking about multimeters or low end oscilloscopes here but rather the higher end; kit that can be used to test complex circuitry such as PCIe systems and really fast DDRx memories (and prove compliance to standards).
I purchased a PCIe analyser for a company some years ago where we did not require anything beyond Gen 1 capability and it was £20k cheaper than paying for the full Gen 2 capability. It could be upgraded as and when that was required.
The equipment I might need may have no requirement (today) for the (for example) DDRx compliance suite or PCIe gen 4 testing. That being the case, I don't have to pay for it even though the equipment may be fully capable of doing the tests in the hardware (Tek front ends have been 63GHz capable for decades).
That can make sense for the test equipment manufacturers and for me as I am not paying for a capability I don't need and the equipment manufacturer does not have to maintain extra physical hardware.
A licence update can unlock that functionality and it has always been a one time install, not a subscription. A lot of test equipment, although networked, does not connect beyond the local network so the 'call home for a server check' is simply not feasible. There are companies working with classified equipment and the network policies prohibit such outside access; the test equipment manufacturers know this.
Another reason for prohibiting / restricting network access is that software updates are highly undesirable in many circumstances.
Other areas that can be unlocked are things like protocol analysers (SPI, I2C, UARTs and the like) although there is no reason (usually) I cannot make my own as these pieces of kit are usually user programmable but it can make sense to simply buy the licence which may be a licence key or a slot in key (sorta like a dongle but much smaller).
There are areas where this sort of thing makes sense.