You need to set the terminator code limit in ESET Endpoint Encryption
Solution
Terminator code limit
The terminator code limit is set when sharing an ESET Endpoint Encryption (EEE) key via email or by network drive/removable memory device. The terminator code limit sets the number of times an encryption key can be passed on to other EEE standalone clients. For example, a code limit of zero will allow the encryption key to be passed on only to the intended recipient. If the code limit is set to three, the original recipient of the encryption key can pass the key on to three other users.
Select the check box next to Set terminator code limit, then enter a value, and then click Next.