That is a known issue.  See

https://ttlc.intuit.com/community/tax-topics/help/turbotax-license-activation-every-time-turbotax-20... 

I bought mine from Amazon - the listing says "The number of computers eligible for installation may vary".  I'm almost certain the install process said I could use it on 5 PCs, but as noted above, that may vary with vendor (it's marked "Amazon Exclusive").  I've only installed it on one so far.

Did it prompt you to enter the authorization code multiple times, as in the link above?  If so, that's a known issue.

Did the listing where you purchased it state the number of installations?

I bought it on turbotaxshopping.net and it didn't specify how many PCs. I installed the 2nd because of preventing my PC to crash.

That might not be a legit seller.  I asked a moderator.

That seems to be the issue. The 2nd installation made TurboTax prompt for activation on my first PC, even after I uninstalled it on my 2nd PC.  Now I have only one non-functional installation on my first PC. I'll keep it that way until the problem is solved by Intuit.

@Franky That website is not a legitimate re-seller. If you did indeed purchase from that site, please send me a copy of your receipt so I can report it. Click into my profile and send me a message. 

As for the product giving you an error for installing, please sign up for the containment posted by VolvoGirl above for updates.