Expiration (Timebomb) on Pre-Release Windows Builds - Why?

My first experience with a pre-release build was back in 2009, with Windows 7 RC.

I noticed something: There was an expiration date for it.
Later i learned that the expiration is called a "Timebomb" and prevents the OS from working properly after a certain date, by deactivating it's license and disabling some important features.

But what exactly is the purpose of it?
Linux alphas, betas and RCs don't expire, OS X ones don't expire as well, as far as i know.

WinInsiderBeta said:

My first experience with a pre-release build was back in 2009, with Windows 7 RC.

I noticed something: There was an expiration date for it.
Later i learned that the expiration is called a "Timebomb" and prevents the OS from working properly after a certain date, by deactivating it's license and disabling some important features.

But what exactly is the purpose of it?
Linux alphas, betas and RCs don't expire, OS X ones don't expire as well, as far as i know.

Because Windows is not FREE but the other OS mention are free.

Thanks for your replies sgage and labeeman.
Now i think i understand.

WinInsiderBeta said:

My first experience with a pre-release build was back in 2009, with Windows 7 RC.

I noticed something: There was an expiration date for it.
Later i learned that the expiration is called a "Timebomb" and prevents the OS from working properly after a certain date, by deactivating it's license and disabling some important features.

But what exactly is the purpose of it?
Linux alphas, betas and RCs don't expire, OS X ones don't expire as well, as far as i know.

If Microsoft leaves it out there in the wild forever, some (not all) people who find it adequate for their particular needs would never pay for it; they'd just continue to use it forever.

There would also be those unscrupulous individuals/companies that would sell a half-baked OS (very few know the difference between a beta and RTM) to unsuspecting victims.

Also, once those unsuspecting victims would start to complain to Microsoft when things didn't work like they thought they should. Black eye for Microsoft.

And finally, sites like TenForums would be inundated with unsuspecting victims needing help with a half-baked OS!

Wynona said:

<SNIP>Also, once those unsuspecting victims would start to complain to Microsoft when things didn't work like they thought they should. Black eye for Microsoft.

And finally, sites like TenForums would be inundated with unsuspecting victims needing help with a half-baked OS!

LOL - I just applied this part of your post to Win 10 RTM situation and thought: Hmmm, it's kinda like Win 10 RTM, with a one year jump on it while it's free schema, is a reverse time-bomb.

I don't necessarily lay the problems entirely at the feet of the OS itself but instead wonder if the whole thing couldn't have been better communicated - maybe that's an unrealistic expectation on my part.