The sentence is “ I thought you might like this” Is the meaning of this - that I thought but you do not like it, or it just represents that in the past moment someone thought you might like it?
The most common use of this phrase is as an idiom when offering something: so in that context it means your last suggestion: "I thought (in the past, but I probably still think) that you might like it [and so I bought it for you/got it for you/am giving it to you"
It could be used literally with either of the meanings you suggest, but this would be unusual unless there was something else that made it clear, such as
I thought you might like this, but obviously I was wrong.
I thought you might like this, and Susan agreed that it was the kind of thing you liked.