My led strip has been up a little more than a month now, hardly a long time, but I prepped the surface with 409 and then IPA, and I made sure to firmly press the strip to the siding after install. It's a pressure activated adhesive, so the more pressure, the better the bond (imho)... no need to go crazy, that will damage the LEDs, but I did wet the heel of my hand, and firmly press and slide along the length of the strip after install, and then again an hour later.
The white outdoor rated gorilla tape I used to cover the hole I drilled in the side of my RV is peeling already, and that tape is EXPENSIVE, I'm rather disappointed... same prep routine as the led strip.