Smartphone life cycles?

[jotat]

Hello,

So I think we're pretty much all aware that the software support for smartphones does not extend ad infinitum. What I'm wondering as a consumer is are there manufacturers that spell out the limits of this support explicitly? I'm thinking along the lines of Microsoft's public life cycles for their software. Implicit support (e.g. Apple supporting products for roughly 3-4 releases of iOS) isn't worth very much if they decide to change their mind about a difficult to support product.

Any help will be apprecited.

I didn't find the right solution from the Internet.

References:
https://techreport.com/forums/viewtopic.php?t=118521
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Thank you.