First you need to copy a key and paste it and try save it then after you can try to activate it,if you have a still problem let us know via https://www.amplethemes.com/contact-us/ here.

When i entered the license key, it displayed this
“cURL error 7: couldn’t connect to host”
now it does not provide an option of entering it again, what should i actually do?

okay can you give us your login details at amplethemes@gmail.com , we will help you to activate a license for your site