In all cases, digital material must include an imprint for as long as both:
the imprint is required by the law
the material remains published
Material remains published for as long as it is being made available to the public or a section of the public. For example, if a post remains available on your social media channels, then it remains published.
Organic material
For organic material, the imprint is required for as long as the published material remains election material.
In many cases the imprint will stop being required once the election is over.
For example, a video saying ‘Vote Grey Party on 1 May’ in relation to an upcoming election will cease to be election material after 1 May when the election is over.
Material saying just 'Vote Grey Party' might continue to be election material even after the election is over, for example if the party is standing in another election in June.
Paid adverts
For a paid advert, an imprint is required for as long as the material remains political material.
How long the material remains political material will depend on who or what your material is reasonably regarded as intended to influence public support for or against. If the material is linked to a particular electoral event or electoral cycle, then it will have a natural end point. For example:
a future candidate could decide not to stand
a candidate ceases to be a candidate after polling day
an elected office-holder ceases to be an elected office-holder when their term ends
support for or against a particular outcome in a referendum cannot be influenced after polling day
Some political material will not have such a clear end point. For example, material promoting support for or against a political party could continue doing that for as long as the party exists.