One of my businesses did large commercial window film installs for decades, no issues with it not staying stuck, I can’t imagine how that would happen unless you ignored all common sense and install instructions. But a decent branded product with a decent lifespan, it’ll likely last you way longer than stated, I have 3-5 year films up that are still going strong after 2-3x that, the only time it’s a problem is when glass is replaced and the new film is slightly different shade wise to its neighbouring windows, but that’s more of an issue on coloured films.