How do I stop Google from bugging me to install the Start page Google app?
You probably configured your Internet Explorer to either block or forget cookies. Google then always treats you as a new user and suggests "improvements".
One reason this might happen (and it did in OP's case) is that the option Internet Options -> Delete browsing history on exit is checked. Unchecking it might solve the problem.
You can either have privacy or convenience here: either accept cookies from google.com, or get used to the banner.
EDIT: Here's how to check if this is cookie-related:
- Dismiss the google popup in IE
- close and repen IE (make sure google.com is NOT your home page, or the test will fail)
- press F12 to open developer console
- go to Network tab
- click Start capturing
- go to www.google.com
- double-click www.google.com in the list of sites that appeared in the Network tab
- check if you have a "Cookie" request header (in the Key column). If not, you have cookies disabled somewhere, and Google should show the annoying pop-up. The cookie should look like this:
