When was it established light travels forever? The range of electromagnetic radiation is indefinite.
When was that established? Doesn't Hubble's limit have an effect?
 A: It hasn't been "determined". It has been determined that photons have a range of at least 46 billion light years. Given that that is the maximum distance we can ever hope to see (or interact with at all), that sphere effectively is the universe, so the range for EM waves is "infinite", at least for all realistic intents and purposes.
Some known mechanisms that have an effect on the range of EM radiation are:


*

*absorption by (partially) opaque medium

*matter creation

*intensity drop to below theoretical minimum detection thresholds


But, in an "idealized" universe where there is no matter at all and an infinite amount of space, AFAIK, there is no known or predicted limit on the maximum range of a photon that does not have enough energy to create matter. 
The classical or relativistic Maxwell's equations (from which the existence of EM waves was first predicted) make no statement on any range limit, neither does anything in quantum mechanics I know of (except for matter creation, but I'm not counting that).
In fact, if you believe in conservation of energy, it's implausible there is a hard limit for general EM waves: into what form would a kHz photon for example convert its energy?
