For Long-Term Fellowships, the eligibility rules of the European Commission for ESR (Early Stage Researchers) apply:
"Early Stage researchers are defined as those who are, at the time of selection by the host instituion, in the first four years of their research careers. This is measured from date when they obtained the degree which would formally entitle them to embark on a doctorate, either in the country in which the research training is provided..."
Also keep in mind the European Commission's conditions of nationality and mobility of researchers, please:
"Researchers can be nationals of any country other than the country of the promises of the host organisation where they will carry out their projects. Additionally researchers must not have resided or carried out their main activity in the country of the host for more than 12 months in the 3 years immediately prior to their recruitment..."
There are fixed-term appointments for up to 36 months. Long-Term Fellowships are available within two main topics
Urgent problems of QSAR/QSPR modeling for REACH
Computational and in vitro screening methods for nano-materials