Shelf life and approach erythromycin-Nystatin in Cetomacrogol cream

We get following recipe:
Erythromycin 4g, Nystatin 4.8 million units in Cetomacrogol cream.
We use the ready-made unbuffered Cetomacrogol cream. But what shelf life can we record for this preparation? There is a lot of disagreement on this. The website of Bassron only uses 1 week, others use 4 weeks in the fridge...

I saw in the answer to a question posted on 4 June 2018 concerning Erythromycin in Cetomacrogol cream that also citric acid is added to it. Is this also necessary in this preparation?