As Taykin mentioned, there's no limitation on creating ELRP sessions.
But be aware that those ELRP packets are CPU generated which means sending out a excessive number of them can cause CPU busy that can cause unexpected behavior.
Let's say you have configured 10 ports as tagged assigned 100 VLANs and ELRP is enabled on all of them.
Then each port need to generate 100 ELRP mcast packets so 1,000 packets total.
If ELRP interval is set to 1 second, ELRP alone generates 1,000 pps which may cause tx congestion.
To avoid this, do not make the ELRP interval too short and add only required ports on the ELRP.
You should be able to create as many ELRP sessions as you can VLANs.
There is no limitation on creating the number of sessions in EXOS. However, this may have some impact with traffic so you may want to increase the interval if there are a high number of sessions involved.