A normal loan has to be paid back with interest. Every now and then there are interest-free loans where only the loan has to be paid back but no interest, e.g. among relatives or friends, but also as a form of state subsidy.
I am looking for the name and examples of interest-only loans from practice where only an interest has to be paid for some period of time, but the loan itself doesn't have to be paid back. I can imagine situations where such loans (or gifts) may make sense (again among relatives or friends or as a form of state subsidy). The idea might be: The borrower must continuously prove that he is serious and worth the gift.