almost all effects are removed when player dies, not sure if there are exceptions
rest will also remove effects, their duration doesn't matter for this, but subtype - supernatural = not removed by rest
dispel magic can also dispel such effect, although this is a bit more lackluster as its influenced by the buggy effect caster level calculation, Im now not 100% sure about it, but I think effect created by module was dispelled but effect created by npc (outside of spellscript) was not. To prevent dispel magic to dispel such effect you need ot make it extraordinary or supernatural.
Transfer between module will remove all effects too.
Skin is possibly better place as this way it wont be affected by any of those issues, however skin has problems with polymorphs and horse system. Polymorphing will not transfer that bonus into polymorph for example.
