Admin panel not showing and Memory error massage time to time

Blank screen on browser.

Time to time message: “Allowed memory size of 33554432 bytes exhausted (tried to allocate 323051 bytes)”
Pages are shown well, the problem only with admin.
No Gregwar installed. No routing set.
Caches clear.
On the localhost, everything works correctly.
Can anyone help, please?

Upgrade from php 5.6 to 7.0 is solved this.