If they were bought him, he would keep them when changing jobs. If they were bought by his employer, then he would leave them. When I retired, I was careful about what things belonged to me and took them home with me, except for a couple of things I would never leave, so left for my colleagues. Here, the work, by law, belongs to the employer, however wrong that may sound. Unlike tools, electronic resources can be left at school and kept by their creator, which sounds like an ideal solution to me.