Good evening Viv and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the memory limit message you have been getting.
I would love to help you with this topic.
I am not sure how you have defined your memory settings, but this is what I am getting from your system information
PHP
max_execution_time = 60
memory_limit = 268435456
upload_max_filesize = 128M
post_max_size = 10M
Normally, the memory limit setting should display more like memory_limit = 256M
So I would definitely recommend digging deeper into this.
Secondly, it looks like you are using a version of PHP that is older than 5.4.x. As a side note, you might want to consider upgrading PHP to version 7 since this is the recommend PHP version (by WordPress).
But at least 5.4.x+ is highly recommended, otherwise things will tend to break and not run smoothly.
Let me know how that goes.
Best regards,
Geoff B.