[CrazyStat]

This is not true in the US. There is a concept of abandonment for trademarks, but it's not that simple, and the concept does not apply to patents. There is a totally different thing called patent abandonment but it has nothing to do with going after infringers.

There is a statute of limitations on patent damages but you don't lose your patent for failing to enforce.

I'm not familiar with UK or European patent law but I expect it's similar in this regard.